General Biology 1

Halves the Chromosome Number, used only for sexual reproduction

1 copy of each chromosome

Sperm & Egg fuse in fertilization to form diploid zygote

23

have two of each type

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

alternate forms of a gene

Many genes exist in several variant forms in a large population & Homologous copies of a gene may encode identical or differing genetic information

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)

Prophase I, Metaphase I, Anaphase I, Telophase I, Cytokinesis, Interkinesis

• Chromosomes:
• Internally duplicate
• Pair up end to end

Line up on the Metaphase plate

Homologous chromosomes split and move toward opposite poles

Daughter Cells have one chromosome from each homolog

• 2 Daughter Cells
• Haploid

• Interphase?
• No replication of DNA

Exchange of genetic material between non sister chromatids during Meiosis I

• Seperation of homologs on the Metaphase plate is random
• Causes random mixing

Chromosomes from each parent cell are combined

offspring adapt to their environment over time

same as Meiosis I: Prophase II, Metaphase II, Anaphase II, Telophase II, Cytokinesis II

chromosomes condense

align at metaphase plate

• Centromeres dissappear
• Sister chromatids seperate

• 4 haploid cells
• All genetically unique

production of gamets

• production of sperm
• all four cells become sperm

• only 1 out of 4 nuclei get cytoplasm
• that one becomes the egg
• others wither away as polar bodies

correct number of chromosomes for the species

incorrect number of chromosomes for the species

incorrect chromosome seperation

only one of a particular type of chromosome

• Three of a particular chromosome
• EX: Down Syndrome

• Inheriting too many/too few X or Y chromosomes
• non-disjunction during Oogenisis or Spermatogenisis
• Deletions
• Duplications
• Translocations
• Inversion

Only one gene is different between the two subjects being crossed

• Alleles seperate during gamete formation
• Each gamete contains only one allele from each pair
• Fertalization gives the offspring 2 alleles for each trait

2

Identical alleles

Different alleles

Literal genetic make up of the trait

The way the genetic makeup of a trait is expressed

Allows us to predict the genotypes and phenotypes of offspring

Medical conditions caused by mutations or mistakes on chromosomes inherited from parents other than problems associated with sex (XY) chromosomes

• AA = has the disorder
• Aa = has the disorder
• aa = does not have the disorder

• AA = does not have the disorder
• Aa = carrier (able to pass on the disease)
• aa = has the disorder

EX: Cross a red and white flower and end up with a pink flower

EX: Blood Type

More than one allele is fully expressed

A single mutant gene affects 2 or more traits that seem to be unrelated

Found in males (XY) Because they do not have an extra X to make up for the mistake on the first X

found that bacteria cells can pass on genetic material even after the bacteria cell is dead

• 4 nuleotides
• 2 Purine bases:Adeniene & Guanine
• 2 Pyramidine bases: Tymine & Cytosine

differs except in identical twins

• double helix (twisted ladder)
• sugar phosphate backbone
• hydrogen bonded bases make up rungs

• each new strand has one original strand and one new strand
• begins at numerous points
• requires DNA polymerase
• happens at the replication fork

• 1. Old DNA unwinds
• 2. Complementary bases are paired
• 3. Bases joined to form the backbone

• in a loop
• produces 2 identical circles
• quick--->20 minutes

• Made up of amino acids
• Makes up protiens
• Proteins carry out functions of a cell

A segment of DNA that specifies the sequence of amino acids of a polypeptide

DNA (which is always being replicated) goes through transcription to become RNA which is then translated into protein

Uracil, Adenine, Cytocine, Guanine

Takes genetic info from DNA to Ribosomes

Makes up ribosomes that read the mRNA

Transfers appropriate amino acid to ribosome when instructed

sequence of 3 bases found on the DNA

• 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

Guanine

Cytocine

Adenine

Tymine

5' to 3'

Guanine cap

adenine tail

sections of mRNA that contain genes that will not be expressed

sections of mRNA that will be expressed in the final product

splicing out the unneeded introns and putting back together the exons

• allows for alternate combinations of Exons
• allows for regulation of gene expression

• Amino acid site (accepts amino acids)
• Exit site (amino acids are ejected here)
• Peptide site (holds everything together)

• Initiation
• Elongation
• Termination

• Small ribosomal subunit attaches to mRNA transcript
• Initiator tRNA attaches to P site
• Large ribosomal subunit attaches to what is already there

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

• 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

DNA wound around this at intervals creates chromosomes

All the members of a specific species occupying a particular area at the same time

study of diversity in terms of allele differences

Pertains to changes found within a population

All the genes of the individuals of a population

• genotype frequencies
• allele frequencies

A random event keeps the majority of individuals from enterering the next generation

When a new population is started from just a few individuals rare alleles will either occur at a higher frequency or be absent

Alleles that will allow for a stronger next generation take presidence over those that would not

• Variation
• Inheritance
• Differential Adaptability
• Differential Reproduction

members of a population differ from one another

many differences are heritable genetic differences

Some differences provide survival

some differences affect the likelihood of successful reproduction

• change in frequencies in the gene pool
• improved fitness of the possibility
• microevolution

females mate with a male who will pass on traits that will improve chances for offspring survival

females choose mates based on male appearance

"Is it benificial to mate if you have to compete?"

• determines which males have the opprotunity to mate and with which females
• sets up the line of defense of the females and territory