AP Biology Unit 5 - Heredity Cheat Sheet (DRAFT) by njags21

his theory us one of partic­ulate inheri­tance

inherited charac­ter­istics are carried by genes

one gamete receives two of the same type of chromosome and other receives no copy

if either aberrant gamete unites w normal gamete during fertil­iza­tion, resulting zygote will have abnormal # of chrom

trisomy

if chromosome is present in triplet

cancer cells grown in culture almost always have extra chromo­somes

4n tetraploid

polyploidy is COMMON in PLANTS

in some cases in respon­sible for evolution of new species

result of crossover is recomb­ination

one map unit distance on chromosome is distance within which recomb­ination occurs 1 percent of the time

recomb­ination frequency

number of recomb­inants / total #offspring X 100

is expressed as a percent

if height is linked to seed color, genes will not segregate indepe­ndently

genes that are adjacent and close to each other on same chromosome tend to move as unit and do NOT segregate

humans have 46 chromo­somes, so have 46 linkage groups

are not linked

trait not identified in either parent appears in F1 generation (recessive when 2 hetero)

absolute certainty is 1

ex: chance of a couple having two boys (1/2 x 1/2)

order matters

boy and then girl is 1/2 x 1/2 = 1/4

1/4 + 1/4 = 1/2

that are NOT on the same chromosome

ex: height segregates indepe­ndently from seed color

recessive is hidden

neither trait is dominant

ex: red Japanese flower crossed w white one

inversion

chromo­somal fragment reattaches to its go chromosome but in reverse orient­ation

polyploidy

when cell or organism has extra SETS? of chromo­somes

embryo

an unborn or unhatched offspring in the process of develo­pment

results in embryo that is a genetic mosaic (some cells have one X activated, some have other)

inacti­vated chromosome condenses into dark spot of chromatin can be seen at the outer edge of nucleus of all somatic cells in female

ex female calico cats (pg 141)

hetero­zygous for some does NOT mean carrier

bell shaped curve

one gene MASKS the expression of the other gene

ex is autosomal recessive disease cystic fibrosis

instead of protecting body, thick mucus builds up in pancreas, lungs, digestive tract

multiple alleles is when there are more than two allelic forms of a gene

are set by specific molecules on surface of red blood cells

A and B are codominant

I^A and I^B

O is recessive

i

ex: MN blood groups in humans

3 diff blood groups (M, N, MN)

single gene locus at which two allelic variants are possible

neither trait is dominant

ex: red Japanese flower crossed w white one

now we can do ones w 2 or more genes

occurs in gamete formation

zygote expresses only one allele of the imprinted gene

extran­uclear genes

located in mitoch­ondria and chloro­plasts

linked to several severe and rare inherited diseases in humans

defects (mutat­ions) in these genes cause weakness and deteri­oration in muscles

in fruit flies, vestigial wings can be altered by temp

many human diseases have a multif­act­orial basis

ex: heart disease, diabetes, cancer, alcoho­lism, schizo­phr­enia, and bipolar disorder

ex is breast cancer allele who don't get breast cancer (pg 138)

44 are autosomes

few genes carried on Y chromosome

can be carrier

recessive sex linked is more common than dominant sex linked

ex for recessive six linked traits

color blindness, hemoph­ilia, Duchenne muscular dystrophy

sons CANNOT inherit sex linked traits from father bc son inherits Y chromosome from him

can occur in somatic cells and be respon­sible for cancer

radiation and certain chemicals cause mutations

but when and where is random

gene mutations

caused by change in DNA sequence

gene mutations cannot be seen under a microscope

karyotype show size, number and shape of chromo­somes

can be used to scan fro chromo­somal abnorm­alities in developing fetuses

ADD ACTUAL MUTATIONS ANDDDDDDD LINKAGE MAPPPP