bio unit 5 (heredity)

interphase

dna replicates in diploid parent cell (results in sister chromatids)

meiosis i (reduction division)

homologous chromosomes split (1 diploid cell to 2 haploid cells)

sister chromatid

identical copy of a chromosome

centromere

attaches sister chromatids

meiosis ii

sister chromatids split (4 haploid cells)

cell cycle

interphase (g1, s, g2), mitosis, cytokinesis

g1 (gap 1)

cell grows larger, copies organelles

interphase

dna and organelles are copied, checkpoints are there to make sure something doesn’t go wrong (90% of cell life spent in interphase)

g1, s, g2

g0 phase

cell cycle arrest; when a cell is no longer dividing nor preparing to divide

s phase

copies dna, duplicates centrosomes

centrosome

organizes microtubules

g2 phase (gap 2)

cell grows more, makes more organelles, rearranges contents to prepare for mitosis

mitosis

PMAT (prophase, metaphase, anaphase, telophase) cell division

prophase

nuclear envelope breaks down, chromosomes condense, and spindle begins to form

metaphase

spindle fibers move chromosomes to middle (sister chromatids attached still), centrosomes move to poles

anaphase

sister chromatids separate and move towards poles, cell elongates

telophase

2 nuclei form, chromosomes decondense, mitosis is complete

cytokinesis

cytoplasm separates (in animals, cleavage furrow, in plants, cell plate)

growth factor

ligand that tells cell to start cell cycle

density-dependent inhibition

cells only divide if there are less nearby cells (e.g. in damaged tissue)

cyclins

bind to cyclin dependent kinases, which phosphorylate target proteins that allow for cell cycle progression

prophase 1

crossing over happens

independent assortment

chromosomes go into one cell or another (meiosis) randomly, contributes to genetic diversity

always happens when genes are on separate chromosomes (b and c)

can happen when genes are far apart enough on the same chromo to cross over

does not happen w/ linked genes (close together on chromo)

genotypic ratio

ex: AA:Aa:aa

phenotypic ratio

dominant:recessive trait

mendel’s law of segregation

offspring get one allele from each parent (contributes to genetic diversity)

test cross

crossing a recessive phenotype with a dominant phenotype to find the latter’s genotype

probability rules

use and rule for each gene in a cross w/ multiple (indep. assortment)

or rule for more than one possibility

codominance

hetero has phenotype of both homos (black + white = speckeled)

incomplete dominance

hetero is a blend of the two homos (red + white = pink)

epistasis

one gene is a light switch for another (one turns on pigment and the other decides the pigment)

polygenic trait

trait controlled by many genes (e.g skin color)

sex linkage

trait carried by X chromosome

gene linkage

genes located on same chromo (some gametes more likely than others, does not sort as expected by indep. assortment)

multifactorial

trait that is combination of genes and env (heart health is genes + smoking and stuff)

non-nuclear inheritance (mitochondrial DNA)

circular like in bacteria, only mother passes on to ALL children

chi square

if less than critical value (FTR)

if greater than critical value (reject null)

df = outcomes -1 (p = 0.05)

if we expect non mendelian inheritance, then not all of the exp values would be =

autosomal recessive pedigree

m and f both affected equally

can skip generations (carrier)

two affected individuals (homo rec) will have all affected offspring

autosomal dominant pedigree

m and f equal

trait can’t skip generations

2 affected parents can have an unaffected kid (hetero)

x linked recessive

m affected more than f

f can only be affected if dad is also affected

x linked dominant

more f affected (usually lethal in m)

if not lethal, dad will pass trait to daughters but not sons

nondisjunction

homologs or sister chromatids don’t separate properly during cell division

aneuploidy

extra or missing chromos

deletion

loss of part of chromo

duplication

extra copy of part of chromo

inversion

reverses dir of part of chromo

translocation

part of one attaches to another chromo