genetics 3

group of individuals with a common set of genes that lives in the same geographic area and actively or potentially interbreed

all the alleles in a population

describes the relationship between allele frequencies and genotype frequency

• that in an ideal population:
• -there is no selection
• -no new alleles arise from mutation
• -there is no migration into or out of the population
• -the population is infinitely large
• -random mating occurs

principle force that shifts allele frequencies within large populations

individuals do not have an equal rate of survival and reproductive success, allele frequencies may change from one generation to the next

an individual organism's genetic contribution to future generations

increase the frequency of the allele to which selective pressure is applied

no such increase is observed in populations not subjected to the selection

a single nucleic acid molecule

largely devoid of associated proteins

much smaller than eukaryotic chromosomes

chromo viruses single/double stranded RNA/DNA

chromo bacteria double-strained DNA, compacted into nucleoid

compacts DNA

mostly closed circular DNA mlcs. in bacteria are slightly underwound and supercoiled

cut one or both DNA strands and wind or unwind the helix before resealing the ends

• -have distinctive banding patterns
• -represent paired homologs
• -are compes of many DNA strands (undergoes many replications w/out strand separation or cytoplasmic division)

areas where DNA has uncoiled and are visible with high level of magnification, found in polytene chromosomes

large and have extensive DNA looping

found in oocytes during meiosis

complex nucleoprotein structure in eukaryotic chromosomes

bound in nucleosomes with histones ( 4 kinds H2A, H2B, H3 AND H4)

needed for histone modifications such as acetylation, methylation, and phosphorylation

eukaryotic domain, uncoiled and active

eukaryotic domain, condensed and inactive

primary constrictions along eukaryotic chromosomes

mediate chromosomal migration during mitosis and meiosis

• short tandem repeats
• -protect the ends of chromo. from being degraded or becoming attached to other chromo.
• -provide a way to replicate DNA at the end of chromosomes

directs synthesis of the telomere repeat sequence to fill the gap

-ribonucleoprotein + RNA, serves template for synthesis of DNA complement

- changes in the total number of chromosomes

-rearrangements of the genetic material either w/in or among chromosomes

variations in chromosome number

organism gains or loses one or more chromosomes and has other than an exact multiple of the haploid set

does not lose a whole set

chromosomes or chromatides fail to disjoin and move to opposite poles during meiosis 1 or 2

cause chromosomal variation

loss of one chromosome

produce 2n-1 complement

occurs in x chromosome, any other autosomes is usually not tolerated in humans and other animals

monosomy for x chromosome

three copies of one chromosome are present, pairing configurations are usually irregular

2n+1

often found in spontaneously aborted fetuses, but monomies are not

3 copies of a chromosome are synapsed

1 bivalent + 1 univalent (unpaired chromo.) may be present

trisomy of chromosome 21

increase incidence w/ increasing maternal age

trisomy 13

extra chromosome 13 disrupts normal course development, causing heart and kidney defects

trisomy 18

more than 2 sets of chromosomes are present from same species (autoployploid) or different species (alloployploidy)

• named by number of sets found
• 3-triploid
• 4-tetraploid
• 5-pentaploid

complete sets of chromosomes are present

forms from hybridization of 2 closely related species

condition which only certain cells in an otherwise diploid organism are polypoid

replication and segregation of chromosomes occur w/out nuclear division

entire organism is normal only some cells mutate

change in total number of chromosomes

rearrangements of the genetic material either w/in or among chromosomes

• -deletions
• -duplications
• -inversions
• -nonreciprocal translocations
• -reciprocal translocations
• -chromosomal breakage

chromosome breaks in one or more places and a portion of it is lost

deletion of chromosome near one end

deletion of chromosome from interior of chromosome

result of unequal crossing over during meiosis or through a replication error prior to meiosis

may play role in evolution

multiple copies of ribosomal RNA genes

rearrangement of the linear gene sequence rather than the loss of genetic info.

ABCD EFG >>> ADCB EFG

requires 2 breaks in chromo. and subsequent reinsertion of inverted segment

may arise from chromo. looping

does not change the relative lengths of the two arms of a chromo.

includes the centromer, does change the length of two arms of chromo.

movement of a chromosomal segment to a new location in the genome

alters location of chromosomal segments in genome

involves exchange of segments between 2 nonhomologous chromo.

has unusual synapsis configuration during meiosis

ABCDEFG+HIJKLM >> HIJCDEFG+ABKLM

breaks at the extreme ends of the short arms of two nonhomologous acrocentric chromo. (chromosome broke in half)

ex. familial down syndrome

down sydrome occasionally runs in families

translocation of chromosome 21

more susceptible to chromosome breakage when cells are cultured in the absence of certain chem. such as folic acid

most common form of inherited mental retardation

sequences are repeated many times w/in eukaryotic chromo.

many different categories of repetitive DNA

used as DNA markers to identify individuals

single-copy noncoding regions

usually not transcribed

specific unique location in the genome

different ppl. have different amount of copies of dna

more that one allele

DNA testing done to determine if they carry a recessive mutation

DNA testing to determine if they have the disease causing mutation

family history of dominate late onset disease

DNA testing on newborn infant , soon develop genetic disease

DNA testing of fetus, tested for chromosomal mutations or gene mutations

DNA testing of embryo produced by in vitro fertilization , test for genetic mutations when parents history put them at high risk

usually multiple embryos

inactive unless bound to cyclins

cyclin helps direct Cdks to target proteins

different cyclin binds to different Cdks

levels peak of cyclin and m-cdk during mitosis

process of programmed cell death

• -embryonic morphogenesis
• -killing by immune effector cells
• -wiring of the developing nervous system
• -regulation of cell viability by hormones and growth factors (cells die if fail to receive signals from other cells)
• -misregulation of apoptosis contributes to cancer, alzheimer's disease, AIDS, ischemia

process of traumatic cell death that results from acute cellular injury

originate from a common ancestral cell that accumulated numerous specific mutations

-cancer

cancer cells manifests itself in gross defects such as translocations, aneuploidy, chromosomal deletions

changes such as DNA metylation and histone acetylation modify gene expression, potentially leading to tumor progression

genes whose products promote cell growth and division

• -transcription factors that stimulate expression of other genes
• -signal transduction mlcs. that stimulate cell division
• -cell-cylce regulators that move through the cell cycle
• -CAN NOT LEAD TO CANCER

mutated version of proto-oncogens

normally regulate cell cycle checkpoints and initiate the process of apoptosis

when mutated cells are unable to respond normally to cell cycle checkpoints or are unable to undergo apoptosis if DNA damage is extensive

encodes a nuclear protein that acts as a transcription factor that represses or stimulates transcription of more than 50 different genes

mutation 50% cancer

mutate RB1 inherited

requires two independent mutational events of RB1 w/in same cell

cancer cells digest components of extracellular matrix and basal lamina that normally inhibit the migration of cells

-must happen for cancer cells to migrate, cancer cell from lung to liver

not able to trigger cancer themselves, does create a higher risk

another mutation in a gene usually needed to fully express cancer

animal viruses that cause cancer

viruses that transform cells into cancer cells

most viruses in animals

substance that causes mutations to occur in proto-oncogenes or tumor suppressor genes

-chemicals, radiation, some viruses, chronic infection

phase in early embryonic development to form three germ layers: ectoderm, mesoderm, endoderm

-epidermis, neural plate, neural crest

notochord, muscle, kidney, blood, heart

-liver, stomach, pancreas, pharynx

developing egg, and most distributed or conc. in specific regions of the cell

expressed during embryo development, often regulated by products of maternal-effect genes

produce large gaps in the embryo's segmentation pattern

cause transformation of body segents

not found in humans=lethal, usually causes spontaneous abortion