ap bio u5

chromosome

chromosome

tightly coiled package of DNA molecules and associated proteins

gene

carries info for protein making (determines organism traits)

allele

different forms of a gene

genotype

set of genes that an organism carries

phenotype

physical/visible traits of an organism

asexual reproduction + result

a single parent reproduces by itself

*results in genetically identical offspring

sexual reproduction + result

two parents combine their genetic material to produce a new organism

*results in genetically different offspring
*MORE ENERGETICALY EXPENSIVE

haploid

one copy of each chromosome (no homologous pairs)

diploid

two copies of each chromosome (homologous pairs)

gametes

haploid sex cells (egg cells in females and sperm in males)

zygote

fertilized egg that results from fusion of male and female gametes

homologous chromosomes

chromosomes that are similar in size and shape + carry the same genes

meiosis

purpose: create gametes (sperm & egg cells) for reproduction

1 diploid parent cell => 4 haploid daughter cells

meiosis results in daughter cells w how many chromosomes?

half the # of chromosomes of the parent cell

prophase I

synapsis: homologous chromosomes stick side-by-side

crossing-over/recombination: chiasma forms & segments are exchanged btwn non-sister chromatids

metaphase I

chromosome pairs RANDOMLY align at center (with spindles attached)

anaphase I

homologous chromosomes move to opposite sides of cell (SISTER CHROMATIDS STAY TGT)

autosomes

any chromosome that isnt a sex chromosome

(22 pairs of chromosomes)

telophase I and cytokinesis

nuclear membrane forms & separates into 2 cells

meiosis II

separate sister chromatids

prophase II

nuclear envelope breaks & chromosomes condense

metaphase II

chromosomes align @ center (single file)

anaphase II

sister chromatids separates

telophase II

nuclear membrane forms

=> FOUR HAPLOID CELLS PRODUCED

mitosis vs meiosis (5 diffs)

MITOSIS: occurs in body cells
MEIOSIS: occurs in sex cells

MITOSIS: produces identical cells
MEIOSIS: produces sex cells (eggs/sperm)

MITOSIS: diploid cell => diploid cell
MEIOSIS: diploid cell => haploid cell

MITOSIS: 1 cell => 2 cells
MEIOSIS: 1 cell => 4 cells

MITOSIS: 1 division
MEIOSIS: 2 divisions

recombination frequency =

map distance btwn genes on the same chromosome

karyotype

A display of the chromosome pairs of a cell arranged by size and shape

epistasis

when one gene modifies the expression of another gene

linked genes

physically located near each other in the same chromosome

*inheritance patterns for the linked genes are usually matched, but depends on genetic distance btwn the two genes

sex-linked genes

genes that are located in only one of the two sex chromosomes

x linked: located in only the x chromosome
y linked: located in only the y chromosome

inheritance of X-linked vs Y-linked traits

X linked:
*depends on whether or male/female carries the allele

Y linked:
*females cannot inherit the allele or transmit the allele
*all sons of affected fathers will be affected

maternal inheritance + examples?

organelles are transferred from mother to offspring

(eg. mitochondria and chloroplast)

incomplete dominance

BLENDING (neither is dominant)

red + white = pink

codominance

BOTH traits are expressed

type A + type B = type AB

phenotypic plasticity

ability of genotype to produce diff phenotypes in response to the environment

nondisjunction + where it can occur

chromosomes fail to separate during meiosis

(anaphase I or II)

translocation

segment(s) of a chromosome break and are lost or reattached to another chromosome

law of dominance

a dominant allele will express itself over a recessive allele

monohybrid cross

a cross in which only one characteristic is tracked

2x2 cross

law of segregation

pairs of alleles for a trait separate when gametes are formed

dihybrid cross (ratio?)

tracks the inheritance of two traits (each has 2 alleles)

4x4 punnett square

9:3:3:1 RATIO
AA : Aa : aA: aa

law of independent assortment

each member of a pair of homologous chromosomes separates independently of the members of other pairs so the results are RANDOM

polygenic inheritance

the combined effects of several alleles lead to continuous variation

mutations

change in DNA sequence (NOT caused by environ conditions)