-
_____ died of cancer in 1951, but biologist have kept her cancer cells alive ever since.
Henrietta Lacks
-
In five minutes our bodies will produce __________ new cells.
10 billion
-
Transcription
produces three different types of RNA molecules
-
Information flows from DNA to RNA during ______ and from RNA to protein during ______
- transcription
- translation
-
RNA differs from DNA in that it contains the sugar _____ and the base _______
-
Transposon
The jumping genes that can move around the genome and sometimes inactivate other genes
-
A virus that infects bacterium is called a ________
Bacteriophage
-
Viruses that break open and kill their host cells upon release are called ________ viruses
Lytic
-
Viruses that use reverse transcriptase are called _____
Retroviruses
-
In addition to the nucleus, what other organelles contain DNA?
- Mitochondria
- Chlorophasts
- both B and C
-
The greatest difference between ancient and modern biotechnology methods is the _______
- level of precision
- rapidity with which organisms can be altered
- the ability to transgress species boundaries
-
The enzyme ______ can link together two pieces of DNA from different sources to produce recombinant molecules
DNA ligase
-
Transgenic pigs, cows, and sheep are created by adding engineered genes
to an externally fertilized zygote
-
The hereditary disorder ________ results in the production of abnormal red blood cells
Sickle cell anemia
-
List, in the correct order, the phases of mitosis
Prophase, Metaphase, Anaphase, Telophase
-
Which of the following is not a benefit of sexual reproduction?
Increased genetic diversity
Energy conservation
Greater likelihood that some offspring will survive
Greater chance the species can survive in a changing environment
Energy conservation
-
Which of the following are haploids?
Somatic cells
Gametes
Zygote
All of these
Gametes
-
Hybrids are of what genotype?
Heterozygous
-
When examining a single gene, what is the predicted genotypic ratio in the F2 generation if two F1 hybrids are crossed?
1:2:1
-
In a testcross, an individual of unknown genotype is crossed with an individual of which genotype?
Homozygous recessive
-
Inversion
A mutation in which a segment of DNA is flipped 180 degrees
-
After DNA replication
Each DNA molecule is composed of one parent and one daughter strand (semiconservative)
-
During DNA replication, what enzymes links the individual nuclotides together to form the new DNA strands?
DNA polymerase
-
What role does DNA ligase play in making recombinant DNA?
It joins the DNA fragments together
-
Which of the following would a researcher use to cut eukaryotic DNA at a particular sequence?
Restriction enzyme
-
For a gene to be expressed in all cells in an animal, the transgenes is put into
The zygote
-
Which of the following has a major effect on phenotype?
Amount of noncoding DNA
Environment
Genotype
Length of RFLPs
- Environment
- Genotype
- Both B and C
-
Which of the following would be considered a chromosomal mutation?
Duplication
Deletion
Translocation
Inversion
- All of the above
- Duplication
- Deletion
- Translocation
- Inversion
-
A lytic infection differs from lysogenic viral infection in that ONLY the lytic does the virus ________
Ruptre the cell soon after infection
-
If meiosis did not occur in sexually reproducing organisms ______
Growth of the zygote would be halted
Mitosis would be suffcient
Gametes would be haploid
The chromosome number would double in each generation
Eggs would be haploid, but sperm would be diploid
The chromosome number would double in each generation
-
Through meiosis
- alternate forms of genes are shuffled
- parental DNA is divided and distributed to forming gametes
- the diploid chromosome number is reduced to haploid
- offspring are provided with new gene combinations
- all of the above
-
Crossing over
Alters the composition of chromosomes and results in new combinations of alleles being channeled into the daughter cells
-
Which organisms did Mendel utilize to work out the laws of segregation and independent assortment?
The garden pea
-
A testcross involves
an F1 hybrid and an organism that is homozygous recessive for that trait
-
The major advantage of sexual reproduction to the population of an organism over asexual reproduction is that ______
Sexual reproduction produces greater genetic diversity
-
When an organism has two different alleles of the same gene it is said to be
Heterozygous
-
The operation of natural selection depends upon the fact that _______
Some individuals have a better chance to produce more offspring
-
Atificial selection occurs when _______
Humans determine which organism will survive
-
Some dogs have erect ears; others have drooping ears. Some dogs bark when following a scent; others are silent. Erect ears and barking are homozygous for both domninat traits is mated to a droopy-eared,silent follower. The phenotypic ratio expected in the F1 generation is _______
100 percent of one phenotype
-
Normal cervical cells---nucleus is small
Pre-cancerous cevical cells---nucleus is larger
Cancerous cevical cells---nucleus is largest
-
Mitosis
- the cell copies its DNA then divides in two
- allows growth and cell replacement in multicelled organisms and creates new individuals in single-celled organisms
- before cell division, it copies DNA
-
In 1889, the German bilogist _______ insisted that the nucleus contained the hereditary material which he called the ______.
- August Weismann
- germ plasm
-
We can describe the process of cell reproduction in terms of the three Ms
- Materials---the small molecules that carry energy or serve as building blocks
- Machinery---the organelles and macromolecular structures needed to carry on cellular processess including DNA
- Memory---the information contained in the nuclear DNA
-
Before a cell divides it usually double its _____
- materials
- machinery
- memory
-
Weismann wrote, Heredity is brought about by the transference from one generation to another, of a substance with a definite...molecular constitution
-
How do prokaryotic (no nucleus) cells divide
- Binary fission
- DNA that is formed in a closed loop
-
Bacteria divide by binary fission in a process that does not involve mitosis
-
Homologous chromosomes
pairs of matching chromosomes
-
After the first growth phase (G1) the DNA doubles (S). The cell then increases materials (G2) in prepartion for the seperation of identical chromatids (mitosis) and the seperation of the two daughter cells (cytokinesis.)
-
Homolog
Each member of the chromosomes pair
-
1. mitosis---the division of the nucleus
2. cytokinesis---the division of the cytoplasm and formation of two seperate plasma membranes
3. interphase---the time when the DNA replicates and the cells grow
Cell Cycle
-
Interphase includes three parts
- G1, the gap or growth phase, between the completion of M and the beginning of DNA synthesis
- S, the period of DNA synthesis when a cell copies its chromosomes
- G2, the gap between the completion of DNA synthesis and the beginning of M
-
Chromatid
- one of the two seperate but connecte bodies that make up a chromosomes at the beginning fo mitosis, when the chromosomes first become visible
- a chromatid contains a single long molecule of DNA
-
Centromere
the two chromatids are joined at a strech of DNA
-
Interphase
The uncoiled chromosomes replicate.
-
Prophase
The chromosomes condense and the nuclear membrane breaks up
-
Metaphase
The chromosomes line up along a central plane of the cell and the asters become visible
-
Anaphase
Spindle fibers pull the chromatids to opposite ends of the cell
-
Telophase
Two new nuclear membranes appear, the asters disintegrate, and the chromosomes uncoil, again becoming invisible
-
Microtubles ________
_________
________
- ______
- _______
- ________
- Proteins that help out with microtubles are actin and myosin
-
Microtubles
hollow tubes made of the protein tubulin
-
Telophase
the last phase of mitosis, the mitotic apparatus breaks down. The chromosomes unwind, and the distinctive bar or string shapes are no longer visible with a microscope
-
Cytokinesis
splitting of cells
-
1. the movement of the chromosomes toward the equator to form the metaphase plate
2. the movement of the separated chromatids toward the poles
3. the movement of the spindle poles away from each other during prophase and again during anaphase
The major players are the microtubles
-
Microtubles move the chromosomes by attaching to the chroatids and growing or shortening
-
Histones
- A set of small, positively charged proteins
- Aid of specialized proteins----the most adundant of which is histones
- Most cells have five types of histones
-
Nucleosome
Two wraps of DNA and a length of DNA linking to the next bead
-
Chromosome banding
a striped pattern visible in a light microscope because dyes darken each band a little differently
-
Animal cells actin filaments form a contractile ring that pinches the cytoplasm in two. In plant cells telophase includes the building of new cell membranes and cell walls between the two daughter cells
-
1. The cells stop dividing during G1 when they run out of free space on which to spread, that is, when neighboring cells all touch each other
2. cells that have proceeded beyond G1 begin to divide when contact with their neighbors ceases
Contact inhibition
-
1. In cell cultures, normal cells divide until they form a single, continuous layer of cells, then stop.
2. If we scrap a "wound" in this monolayer of normal cells, cells from the edge move into the open space and divide until the wound is filled
3. Normal cells stop dividing when they come into contact with other cells
4. Cancer cells do not self regulate in this way Instead they conintue to divide even after they come into contact with other cells, piling up on top of one another
-
Meiosis
cells produce daughter cells (eggs and sperm) with only half the normal number of chromosomes
-
Genetics
The study of inheritance
-
Transmission genetics
the study of how variation is passed from one generation to the next
-
Molecular gentics
the study of DNA carries genetics instructions and how cells carry out these instructions
-
Phenotype
encompasses both physical and behavioral characterstics
-
Genotype
Particular collection of genes of a cell or organisms
-
Four important points underlie the universiality of genetic inheritance in eukaryotes
- 1. All cellular organisma use DNA as the genetic material
- 2. The DNA of all eukaryotic organisms is organized into chromosomes
- 3. Almost all chromosomes exist in pairs at some time during a sexual life sycle
- 4. These pairs of chromosomes behave in the same ways during meiosis and at fertilization
-
Phenotypic plasticity
frogs eating each other then growing lungs
-
Diploid
Cells that contain paired sets of chromosomes
-
Gametes
An organism that reproduces sexually passes the half-set of chromosomes to its offspring in specialized reproductive cells
-
Haploid
Each gamete is haploid that it carries a single set of chromosomes----in humans 23
-
Syngamy
or ferilization, the union of the two haploid gametes (one from each parent) to form a single diploid cell called a Zygote
-
Crossing over
At the very beginning of meiosis, during prophase I, homologous chromatids pair up in synapis. While they are paired up, the chromatids may break at places called chiasma and exchange equivalent pieces. The result is new combinations of genes on each chromatid
-
All kids can be different because of crossing over
-
Down Syndrome
- Extra chromosome Number 21
- Has 47 instead of 46
-
Trisomy 21
The presence of three rather than two, copies of chromsome 21
-
Nondisjunction
Occasionally separation of homologous in anaphase I and chromatids in anaphase II fails to occur
-
Down syndrome
a disorder that leads to mental retardation and the abnormal development of the face
-
-
The X and Y chromosomes are called sex chromosomes. The rest of the chromosomes are called autosomes.
A human cell has 22 pairs of autosomes and 1 pair of sex chromosomes
-
Alleles
Alternate versions of the same gene
-
A human cell has 22 pairs of autosomes and 1 pair of sex chromosomes
-
44 autosomes chromosomes
2 sex chromosomes
46 total
-
chemidophorus
species in desert that has no males--only females
-
Chemidophorus by parthenogenesis
Female lays deployed egg basically cloning
-
Homozygous
- If an individual has two copies of the same alleles
- TT tt
-
Heterozygous
- If an individual has two different alleles of a gene
- Tt
-
Cross breeding
method of breeding two genetically distinct organisms
-
Gregor Mendel
father of genetics
-
Dominant
when it alone determines the phenotype of a heterozygote
-
The seven traits of peas
- Seed shape
- Pod shape
- Seed color
- Pod color
- Flower color
- Flower position
- Stem length
-
Recessive
when it contributes nothing to the phenotype of a heterzygote
-
monohybrid cross
only concerned with one trait
-
Incomplete dominance
both alleles are expressed
-
Pea flowers carry both male and female parts
-
Principle of segregation
Each sexually reproducing organisms has two genes for each characterisic; these two genes segregate (or seperate) during the production of gametes
-
Backcross
Instead of allowing F1 heterozygotes to self-pollinate, he crossed them with the homozygous recessive stock
-
-
-
Principle of independent assortment (proven false later)
Each pair of genes is distributed independently from every other pair during the formation of the gamtes
-
Walter Sutton's six rules of inheritance
- 1. Chromosomes come in pairs. One chromosomes comes from the mother and one from the father. We now call these "homologous" pairs
- 2. Synapsis is the pairing of homologous maternal and paternal chromosomes. These pairs seperate into different daughter cells during meiosis
- 3. The chromosomes are not broken down and created anew during each cell cycle
- 4. The chromosomes carry genes
- 5. Meiosis createsnew combination of genes in each generation. During meiosis either homolog may end up in either new cell, reguardless of the way all the other homologous chromosomes divide. The accounts for Mendels's principle of segeration
- 6. Each chromosome carries a different set of genes, and all of the genes on one chromosomes are inherited together. That different chromosomes are inherited independently accounts for Mendel's principle of indeperdent assortment
-
Crossing over is the physical exchange of material between homologous chromosomes.
-
The chance that any two genes on a chromosome will recombine is proportional to the physical distance between them
-
Four bases:
- Purines: Adenine (A) and Guanine (G)
- Pyrimidines: Cytocine (C) and Thymine (T)
-
Sugar-phosphate backbone
Nucleotide
-
HA oxidase (Homoaxidary Acid)
Enzyme that helps breaks down HA
-
alkaptonuria
inherited disease that causes urine to turn black when parents were first cousins
-
Heploid
Only 1st set of chromsomes
-
George Beadle and Edwared Tatum chsoe to study a simple fungus, the pink bread mold Neurospora
Their work suggested that every gene somehow affects the function of a single enzyme
-
Sickled and standard red blood cells
- 1 in 165 have two copies of the allele and have the disease
- RBC live 120 days
- SBC live 40 days
-
Sickle cells have resistance against malaria
75% protected
25% unprotected
Sickle cells comes from the cresent of sickle shape of the red blood cells
-
Bacteriophage
Phages are a kind of virus that infect bacteria. Viruses are assemblies of protein and DNA capable of forcing host cells to make more viruses
-
Life cycle of a phage
- 1. Phage attaches to surface of bacterium
- 2. Phage injects its DNA into bacterium
- 3. DNA inside bacterium
- 4. Phage DNA directs host cell to produce new phage proteins and phage DNA
- 5. Complete, mature phages assemble
- 6. Cell wall bursts, releasing 100 to 200 new phages
-
Viruses never have both DNA and RNA---they have one but not both
-
In the Hershey-Chase experiment, radioactive DNA from a phage shows up inside the infected bacterium. Radioactive protein stays outside. This 1952 experiment finally convinced bilogist that DNA not prtein, was the gentic material (later work showed that a few viruses use RNA as their genetic material)
-
According to this model, DNA replication is semiconservatice. That is half of each parent molecule is present in each daughter molecule. Each new DNA molecule is really only half old and half new
(proven wrong)
-
DNA replication is semiconservative; when DNA replicares, each half of the double helix acquries a new mate
-
At one time the biologist thought that DNA replication was conservative. Both halves of the old molecule stayed together while the whole new molecule was created.
In fact DNA replicates, each half of the old double helix acquires a new mate.
-
3 enzymes that replicate DNA
- 1. Helicase
- 2. Polymerase
- 3. Ligose
-
-
DNA polymerase
approaches RNA primer and replaces with DNA
-
DNA ligase
- connects Okazaki fragments
- Biological glue
-
Bacteria
Not a double helix but circular DNA
-
Replication of DNA
Replication begins at the origin of replication then works in both direction around the circle
-
Cellmatic--changes just in the cell
Somatic--gentic material is unchanged
-
Mutations
Permanent changes in DNA
-
The cause of mutations
Radiation kills genes
-
Occationally mutations occur because DNA polymerase places the wrong nucleotide in a sequence during the synthesis (S) phase of the cell cycle
-
Mutagens
- Increase the rate of mutations.
- Ultra-violet light, high-energy radiation such asa x-rays and many chemicals can all act as mutagens
-
Point Mutations
- Change one or several nucleotide pairs.
- 1. Base Substitutions
- 2. Insertion
- 3. Deletion
-
Chromosomal Mutations
- Change relativiely large regions of chromosomes
- 1. Deficiencies
- 2. Translocations
- 3. Inversions
- 4. Duplications
- 5. Polyploidy
-
Base Substitution
The replacement of one base (nucleotide) by another
-
Insertion
The addition of one or more nucleotides
-
Deletion
The removal of one or more nucleotides
-
Deficiencies
Deletions that are larger than a few nucleotides
-
Translocations
In which part one chromosome is moved to another chromosome
-
Inversions
In which a segment of a chromosome is flipped 180 degrees
-
Duplications
In which part of a chromosome appears twice
-
Polyploidy (aneuploidy)
Chromosomes have doubled but cytokenisis didnt happen and there was no cell division
-
Trisomy
The presence of three copies of a certain chromosome
-
Healthy cells are quick to repair damaged DNA
- 1. Damage caused by UV light
- 2. Damage is removed by enzyme
- 3. DNA polymerase creates a new sequence
- 4. DNA ligase seals the nick
-
Codon
A group of three nucleotides that specifies a single amino acid within a polypeptide
-
Genetic Code
- Clearly specifies which nucleotide sequences correspond to which amino acid sequences
- A language with 20 amino acid letters
-
The genetic code is also said to be universal
- because all eukaryote orgainisms use the same code.
- For example, when globin RNA from rabbit red blood cells is added to wheat germ cells, the wheat cells make rabbit globin, demonstrating that wheat cells and rabbit cells use the same genetic code to translate RNA into protein
-
The protein making machinery of wheat plant can synthesize blood proteins normally found only in rabbits
-
Francis Crick
Central dogma of molecular biology: DNA specifes RNA which specifies proteins
-
DNA specifies RNA which specifies protein. DNA in the nucleus is transcribed into RNA. Outside the nucleus in the cytoplasm, ribosomes traslate RNA into polypeptides.
In prokaryotes, which lack a nucleus, both transcription occur in the cytoplasm
-
Messenger RNA (mRNA)
this is what The RNA copy of the information from DNA is composed of
-
Transfer RNAs
The mRNA codons bind to the tRNA not to the amino acid its self
-
1. Transcription
2. Messenger
3. Transfer
- 1.messenger- info to ribsome
- 2. ribosomes- works with ribosomes
- 3. transfer- brings amino acids to sight of ribosomes
-
DNA -----________-----RNA------________--------Polypeptide
- Transcription
- Translation
-
Transcriptional control
when cells increase or decrease the amount of mRNA transcribed from the DNA
-
Translational control
A cell varies the rate at which it translates different mRNA
-
Barbara McClintock
discovered Transposon
-
Transposon
- to describe these genes that jumped around the genome
- "jumping genes"
- Point mutations
-
Mobile Genes
genes that move around
-
Plasmids
can exist as simple loops of DNA sparate from the host cell's DNA--usually in prokaryote or yeast cells---that pass from cell to cell
-
Virus
an assemblage of nucleic acid (DNA or RNA) and proteins
-
Viruses come in many shapes
-
Protein coat
Surround the gentic material
-
Life of a Bacteriophage
- 1. Phage attached to surface of bacterium
- 2. Phage injects its DNA into bacterium
- 3. DNA is inside bacterium
- 4. Phage DNA directs host cell to produce new viral proteins and DNA
- 5. Complex, mature phages assemble
- 6. Cell wall bursts, releasing 100 to 200 new phages
-
The life of a phage
A phage attached to the surface of its bacterial host and injects its DNA inside. The host cell transcribes and translated the phage genes to make more phages, which eventually burst from and kill the host cell
-
Viruses have two ways to duplicate
- 1. Autonomous replication
- 2. Intgrated replication
-
Autonomous replication
the genes are separate from the DNA of the host cell and can replicate even when the host DNA is not replicating
-
Integrated replication
The genes become integrated into the hosts DNA and are replicated along with those of the host
-
Episomes
Viruses and plasmids that switch back and forth between integrated and autonomous replication
-
Plasmid
A small piece of circular DNA or RNA in a bacterial or yeast cell that included from 3 to 300 genes
-
Conjugation
Two bacteria temporarily attach to one another and exchange genetic meterial
-
Conjugation
These genes encode an enzyme that makes the cell reisistant to an antibiotic
-
Transposase
Enzyme which inserts the transposon into new places
-
complex transposons
lie near each other on the host genome, they jump together carrying with them any genes that lie between them
-
Viruses that cause tumors are a special case
tumor viruses multiply only when their eukaryotic host do
-
DNA tumors viruses integrate thier DNA into the DNA of eukaryotic cells. Then disrupt the cell cycle forcing t=infected cells into excessive cell division resulting in growth of a tumor
-
Lytic Cycle
DNA is separate from that of its host a lyses its host
-
The prophage and the lytic cycle together make up the viral ___________
Lysogenic cycle
-
Lysogenic cycle
- 1. Phage DNA enters host cell
- 2. Phage DNA integrates into host cell DNA
- 3. Phage DNA replicates along with bacterial DNA
- 4. Cycle repeats
-
Lytic Cycle
- 1. Bacterium makes new phage DNA and protien
- 2. Bacterium assembles new pages
- 3. Cell burst releasing new phages
-
Reverse transcriptase
Copies RNA into DNA
-
T cell
HIV virus bind to T cell and only cell in body
-
How retroviruses reproduce
- 1. Retrovirus membrane fuses with host cell membrane
- 2. Viral coat breaks up
- 3. Reverse transcriptase makes complementary single strand of DNA
- 4. Host cell makes complememtnray copy of DNA which integrates into host cell DNA
- 5. Host cell transcribes viral DNA into mRNA
- 6. Host cell translates viral RNA into viral proteins
- 7. Viral proteins and RNA assemble
- 8. Host cell releases new retrovirus
-
-
Over evolutionary time, viruses could have evovled either from free-living cells or from transposons
-
AZT increases the number of proteins in the body so ammune sstem stays normal
-
Mitochonria and cholorplast which have their own DNA separate from the nuclear DNA evolved when a prokaryote ancestor came to live in symbiosis with another cell. The gentic systems of mitochondria and chloroplasts differ from those in both eukaryotic nuclear DNA and in prokaryotes suggesting that these organelles have an ancient and separate origin
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