AP BIO unit 5

Genes

Genes

segments of DNA

Locus

specific location of gene on a certain chromosome

Asexual reproduction

one parent produces identical offspring by mitosis

Sexual reproduction

two parents make unique offspring with combination of genes

Karyotype

ordered display of the pairs of chromosomes

Homologus Chromosomes

similar chromosomes

Autosomes

22 pairs of chromosomes that do not determine sex

Sex chromosomes

X and Y, (XX=female), (XY=male)

Diploid Cell (2n)

two sets of chromosomes

Haploid Cell (n)

one set of chromosomes

Fertilization

union of sperm and egg

Zygote

fertilized egg

Meiosis 1

homologus chromosomes seperate (2n → n)

Meiosis 2

sister chromatids seperate (n → n)

4 Phases of Meiosis 1

Prohase 1, Metaphase 1, Anaphase 1, Telophase 1 and cytokinesis

Prophase 1

Chromosomes condense, homologus chromosomes pair up (synapsis), non-sister chromatids exhange DNA segments (crossing over)

Metaphase 1

tetrads line up in middle, microtubules from each pole attach to tetrads kinetochores

Anaphase 1

pairs of homologus chromosomes seperate, sister chromatids remain attached

Telophase 1

each half of the cell has a haploid set of chromosomes; each chromosome still consists of two sister chromatids

Cytokinesis 1

forms two haploid daughter cells, cleavage furrow forms (animal cells), cell plate forms (plant cells)

4 Phases of Meiosis 2

Prohase 2, Metaphase 2, Anaphase 2, Telophase 2 and cytokinesis

Prophase 2

spindle apparatus forms

Metaphase 2

sister chromatids line up in middle, microtublues of each pole attach to kinetochores of sister chromatids

Anaphase 2

sister chromatids seperate

Telophase 2

nuclei form, chromosomes decondense

Cytokinesis 2

seperates cytoplasm

Meiosis 1 and 2 full process photo

(photo)

Mitosis v Meiosis comparison photo

(photo)

3 Mechanisms of Genetic Variation

Independent assortment, Crossing over, Random fertilization

2^n

number of combinations for independent assortment

Recombinant Chromosomes

what chromosomes are after crossing over

Alleles

specific variations of genes

Dominant Allele

always shows in phenotype when inherited (AA , Aa)

Recessive Allele

only shows in phenotype when dominant is not inherited (aa)

Genotype

combination of inherited alleles

Homozygous

genotype of 2 same alleles (AA , aa)

Heterozygous

genotype of 2 different alleles (Aa)

Phenotype

physical result of genotype

Multiplication rule

independent events occuring at the same time, this and that together (probability of landing tails on 3 seperate coins, 0.5 x 0.5 x 0.5)

Addition rule

mutually exclusive events, this or that

Complete Dominance

normal inheritance pattern

Incomplete Dominance

heterozygous phenotype is a blend of dominant and recessive (red + white = pink)

Codominance

two dominant alleles affect phenotype in seperate ways (stripes)

Pedigree

family tree that describes inheritance patterns of specific traits

Carriers

heterozygous individuals who show dominant allele but carry recessive allele