fertilization

when a haploid sperm cell fuses with haploids egg cell

the first cell

all somatic cells have copies of all of the zygote's 46 chromosomes

homologous pairs have...

same centromere location, length, genes, banding pattern (zebra stripes)

What is the perpetuation of life based on?

cellular reproduction / division

What is Rudolf Virchow's modern cell theory?

the cell is the smallest living unit of all organisms, all living things are made of cells, all cells come from pre-existing cells

parent cell

produces daughter cells via meiosis or mitosis

binary fission

prokaryotic cell division; plasma membrane and cell wall grow inward to divide in half after DNA is doubled

genes of prokaryotes

single chromosomes, circular, smaller, simpler

hypothesis for 2 daughter chromosomes separating in prokaryotes

new plasma membrane grows between 2 sites where chromosome duplicates are attached OR chromosomes actively move away via unknown mechanism

kinetochore

SPECIFICALLY the protein structure each sister chromatid has, which holds chromosomes together at centromere

centromere

where the sister chromatids join together

gametogenesis

another name for meiosis

spermatogenesis

when sperm cells are made

oogenesis

when eggs are made, produces only ONE ovum, other 3 are polar bodies

polar bodies

the other 3 cells produced, degenerate since have very little cytoplasm (females conserve as much for the one ovum)

ovum

surviving gamete in oogenesis

sources of genetic variation

crossing over (P1), independent chromosome orientation (M1), random fertilization, chromosomal nondisjunction, chromosomal mutations

independent orientation

the random / independent arrangement of homologous chromosomes (tetrads) at metaphase 1 affects the resulting gametes (50/50 for each of getting mother or father side)

gamete combination rule

2^n in any organism (n = haploid number)

crossing over

the exchange of corresponding segments between 2 homologous chromosomes during the process of synapsis in prophase 1

chiasma

sites of crossing over

synapsis

formation of tetrads in P1; occurs when homologous chromosomes pair up during meiosis

genetic recombination

the production of a gene combination different from what the original chromosome carried

recombinant

result of chromatid with crossing over, different than parental genotype

parental

chromatid without crossing over, same as parental genotype

karyotype

an orderly display of magnified images of independent chromosomes

What happens with most abnormal chromosome numbers, dominant genetic diseases, and incredibly harmful mutations?

miscarriage / abortion

What happens with missing autosomes?

always death by miscarriage

down syndrome (trisomy 21)

3 copies of chromosome 21, shorter life span, round face, short stature, mental disability, most sterile, susceptible to disease

nondisjunction

chromosome pair fails to separate --> aneuploidy (abnormal number of chromosomes in cell)

nondisjunction in meiosis I

100% of gametes have abnormal chromosomes numbers

nondisjunction in meiosis 2

50% of gametes have abnormal chromosomes numbers

meiosis in women

begins before born, only 1 matures per month = period, arrested mid-meiosis for decades leads to errors around 35+

XXY

Kleinfelter syndrome in males, small sterile testes, normal intelligence, breast enlargement

XO

Turner syndrome in females, short, web of skin between neck and shoulders, sex organs don't fully mature so sterile

chromosomal deletion

fragment lost, most serious, cri du chat syndrome

chromosomal duplication

fragment joints to homologous chromosome

chromosomal inversion

fragment reattaches to OG chromosome in reverse direction

chromosomal translocation

fragment attached to nonhomologous chromosome

nonreciprocal translocation

fragment just breaks off and attached, no exchange

reciprocal translocation

2 nonhomologous chromosomes exchange segments (e.g. in down syndrome can result from only part of a 3rd chromosome 21)

chronic myelogenous leukemia (CML) / Philadelphia X

chromosome reciprocal translocation in bone marrow, gene activated when chromosome 22 switches with a fragment of chromosome 9

Law of Dominance

one trait masks the effects of another trait

Law of Segregation

each gamete gets only one of the copies of each gene

dihybrid cross between heterozygotes

9 dominant dominant; 3 dominant recessive; 3 recessive dominant; 1 recessive recessive

trihybrid cross

3 different characteristics involved, find all separately in punnett square and then use rule of multiplication

Rule of Multiplication / Product Rule

events occurring SIMULTANEOUSLY

Rule of Addition / Sum Rule

EITHER event will occur

recombination frequency

percentage of recombinants: recombinants over total offspring, all times 100

sex-linked gene

any gene located on a sex chromosome (usually X)

red-green color blindness

X-linked (males), malfunction of light sensitive cells in eyes

hemophilia

X-linked (males), bleed excessively, abnormal blood clots

Duchenne muscular dystrophy

X-linked (males), progressive weakening / loss of muscle tissue

phenotypic plasticity

two individuals with the same genotype have different phenotypes because they are in different environments, adapt to local environmental factors (e.g. temperature, nutrition, disease, physical activity; height and weight in humans, soil pH in flower color, seasonal fur color in arctic animals, sex determination in reptiles)

photoperiod

how much light is received during the day (arctic hare color change is linked to photoperiod)

X-Y system

males determine offspring

X-O system

males determine offspring by not giving chromosome

Z-W system

females determine offspring

haploid / diploid system

male fertiliztion determines offspring, unfertilized / haploid eggs are male, fertilized / diploid eggs are female

monoecious

plants that produce both sperm and eggs (e.g. corn, pea plants)

hermaphroditic

animals that produce both sperm and eggs (e.g. garden snails, earthworms)

wild-type traits

prevail in nature, not necessarily dominant; majority recessive in nature

cystic fibrosis

recessive genetic disease, most common U.S. lethal disease, excess mucus in lungs cause breathing problems

phenylketonuria (PKU)

recessive genetic disease, phenylalanine accumulation in blood, mental disability

sickle-cell disease

recessive genetic disease, sickle red blood cells, tissue damage, pleiotropy and codominance

Tay-Sachs

recessive genetic disease, lipid accumulation in brain cells, mental deficiency, blindness, childhood death

Huntington's disease

dominant genetic disease, nervous system degeneration, begins in middle age