-
Meiosis
Halves the Chromosome Number, used only for sexual reproduction
-
haploid gametes
1 copy of each chromosome
-
Gametes
Sperm & Egg fuse in fertilization to form diploid zygote
-
Humans have how many different types of chromosomes?
23
-
Diploid cells
have two of each type
-
Homologous Chromosomes
Same length, centromeres positioned in the same place, one from father, one from mother(paternal/maternal homolog), similar banding patterns when stained, genes controll same trait at same position
-
Alleles
alternate forms of a gene
-
Homologous Chromosome Pairs
Many genes exist in several variant forms in a large population & Homologous copies of a gene may encode identical or differing genetic information
-
An individual may have:
Identical alleles for a specific gene on both homologs (homozygous for the trait), or A maternal allele that differs from the corresponding paternal allele (heterozygous for the trait)
-
Meiosis I
Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Interkinesis
-
Prophase I
- Chromosomes:
- Internally duplicate
- Pair up end to end
-
Metaphase I
Line up on the Metaphase plate
-
Anaphase I
Homologous chromosomes split and move toward opposite poles
-
Telophase I
Daughter Cells have one chromosome from each homolog
-
-
Interkinesis
- Interphase?
- No replication of DNA
-
Crossing Over
Exchange of genetic material between non sister chromatids during Meiosis I
-
Independent Assortment
- Seperation of homologs on the Metaphase plate is random
- Causes random mixing
-
Fertalization
Chromosomes from each parent cell are combined
-
Significance of Genetic Variation
offspring adapt to their environment over time
-
Meiosis II
same as Meiosis I: Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis II
-
Prophase II
chromosomes condense
-
Metaphase II
align at metaphase plate
-
Anaphase II
- Centromeres dissappear
- Sister chromatids seperate
-
Telophase II & Cytokinesis II
- 4 haploid cells
- All genetically unique
-
Gametogenesis
production of gamets
-
Spermatogenisis
- production of sperm
- all four cells become sperm
-
Oogenisis
- only 1 out of 4 nuclei get cytoplasm
- that one becomes the egg
- others wither away as polar bodies
-
Euploid
correct number of chromosomes for the species
-
Aneuploid
incorrect number of chromosomes for the species
-
Aneuploid is the result of:
incorrect chromosome seperation
-
Monosomy
only one of a particular type of chromosome
-
Trisomy
- Three of a particular chromosome
- EX: Down Syndrome
-
Changes in Sex Chromosomes can be the result of:
- Inheriting too many/too few X or Y chromosomes
- non-disjunction during Oogenisis or Spermatogenisis
- Deletions
- Duplications
- Translocations
- Inversion
-
Monohybrid Cross
Only one gene is different between the two subjects being crossed
-
Law of Segregation
- Alleles seperate during gamete formation
- Each gamete contains only one allele from each pair
- Fertalization gives the offspring 2 alleles for each trait
-
Each trait is controlled by how many alleles?
2
-
Homozygous
Identical alleles
-
Heterozygous
Different alleles
-
Genotype
Literal genetic make up of the trait
-
Phenotype
The way the genetic makeup of a trait is expressed
-
Punnett Square
Allows us to predict the genotypes and phenotypes of offspring
-
Autosomal Disorders
Medical conditions caused by mutations or mistakes on chromosomes inherited from parents other than problems associated with sex (XY) chromosomes
-
Autosomal Dominant
- AA = has the disorder
- Aa = has the disorder
- aa = does not have the disorder
-
Autosomal Recessive
- AA = does not have the disorder
- Aa = carrier (able to pass on the disease)
- aa = has the disorder
-
Incomplete Dominance
EX: Cross a red and white flower and end up with a pink flower
-
Multiple Allilic Traits
EX: Blood Type
-
Codominance
More than one allele is fully expressed
-
Pleiotrophy
A single mutant gene affects 2 or more traits that seem to be unrelated
-
X-Linked Diseases
Found in males (XY) Because they do not have an extra X to make up for the mistake on the first X
-
Fredrick Griffith
found that bacteria cells can pass on genetic material even after the bacteria cell is dead
-
DNA structure
- 4 nuleotides
- 2 Purine bases:Adeniene & Guanine
- 2 Pyramidine bases: Tymine & Cytosine
-
Amounts of A, G, T, C in individuals ________.
differs except in identical twins
-
Watson and Crick Model
- double helix (twisted ladder)
- sugar phosphate backbone
- hydrogen bonded bases make up rungs
-
DNA Replication (Eukaryotic)
- each new strand has one original strand and one new strand
- begins at numerous points
- requires DNA polymerase
- happens at the replication fork
-
Steps of DNA Replication (Eukaryotic)
- 1. Old DNA unwinds
- 2. Complementary bases are paired
- 3. Bases joined to form the backbone
-
DNA Replication (Prokaryotic)
- in a loop
- produces 2 identical circles
- quick--->20 minutes
-
Polypeptide
- Made up of amino acids
- Makes up protiens
- Proteins carry out functions of a cell
-
Gene
A segment of DNA that specifies the sequence of amino acids of a polypeptide
-
Central Dogma
DNA (which is always being replicated) goes through transcription to become RNA which is then translated into protein
-
RNA types
Uracil, Adenine, Cytocine, Guanine
-
Messenger RNA
Takes genetic info from DNA to Ribosomes
-
Ribosomal RNA
Makes up ribosomes that read the mRNA
-
Transfer RNA
Transfers appropriate amino acid to ribosome when instructed
-
Codons
sequence of 3 bases found on the DNA
-
Properties of the Genetic Code
- Universal: all organisms code the same way
- Degenerate: more than one codon=same amino acid
- Ambiguous: codon only codes for one amino acid
- Contains start and stop codons
-
Cytocine binds with ________.
Guanine
-
Guanine binds with __________.
Cytocine
-
Tymine binds with ____________.
Adenine
-
Adenine binds with ___________.
Tymine
-
Sythesis occurs in what order?
5' to 3'
-
What is found on the 5' end of the mRNA?
Guanine cap
-
What is found on the 3' end of the mRNA?
adenine tail
-
Introns
sections of mRNA that contain genes that will not be expressed
-
Exons
sections of mRNA that will be expressed in the final product
-
RNA splicing means what?
splicing out the unneeded introns and putting back together the exons
-
Why are Introns included in mRNA?
- allows for alternate combinations of Exons
- allows for regulation of gene expression
-
rRNA Binding sites
- Amino acid site (accepts amino acids)
- Exit site (amino acids are ejected here)
- Peptide site (holds everything together)
-
Stages of Translation
- Initiation
- Elongation
- Termination
-
Initiation
- Small ribosomal subunit attaches to mRNA transcript
- Initiator tRNA attaches to P site
- Large ribosomal subunit attaches to what is already there
-
Elongation
amino acids are brought in and added to the polypeptide by tRNA who reads the mRNA transcript in order to pick out the correct amino acid
-
Termination
- tRNA reads the stop codon
- the last amino acid is added and the spent tRNA is sent to the E site
- Polypeptide released, and ribosome falls apart
-
Histones
DNA wound around this at intervals creates chromosomes
-
Population
All the members of a specific species occupying a particular area at the same time
-
Population Genetics
study of diversity in terms of allele differences
-
Microevolution
Pertains to changes found within a population
-
Gene Pool
All the genes of the individuals of a population
-
Gene pools can be described in terms of __________.
- genotype frequencies
- allele frequencies
-
Bottleneck Effect
A random event keeps the majority of individuals from enterering the next generation
-
Founders Effect
When a new population is started from just a few individuals rare alleles will either occur at a higher frequency or be absent
-
Natural Selection
Alleles that will allow for a stronger next generation take presidence over those that would not
-
Natural Selection requires:
- Variation
- Inheritance
- Differential Adaptability
- Differential Reproduction
-
Variation
members of a population differ from one another
-
Inheritance
many differences are heritable genetic differences
-
Differential Adaptability
Some differences provide survival
-
Differential Reproduction
some differences affect the likelihood of successful reproduction
-
Natural Selection results in:
- change in frequencies in the gene pool
- improved fitness of the possibility
- microevolution
-
Good Genes Hypothesis
females mate with a male who will pass on traits that will improve chances for offspring survival
-
Runaway Hypothesis
females choose mates based on male appearance
-
Cost benifit analysis
"Is it benificial to mate if you have to compete?"
-
Dominance Hierarchy
- determines which males have the opprotunity to mate and with which females
- sets up the line of defense of the females and territory
|
|