biology test dominance and recessive genes

genetics

the study of heredity

gene

a segment of DNA that determines a trait

alleles

different gene possibilities for the same trait

dominant gene

prevents the other gene from showing, is stronger

recessive gene

does not show even though it is present, is weaker

homozygous/purebred

TT or tt

heterozygous/hybrid

Tt

Genotype

combination of genes an organism has

phenotype

physical appearance resulting from genetic make-up

P (parental generation)

the original pair of plants

F1 (first filial generation)

the offspring of the P generation

F2 (second filial generation)

the offspring of the F1 generation

punnet squares

used to predict the possible gene makeup of offspring

Tt

what genotype would a heterozygous short haired guinea pig have? (short hair is dom)

TT

what genotype would a homozygous short haired guinea pig have?

tt

what genotype would a long haired guinea pig have?

incomplete dominance

neither allele for a gene dominates, blend of homozygous parents, has primes RR, R’R’, and RR’

codominance

both alleles are expressed equally, heterozygous offspring show both traits, no primes, RR, SS, RS

multiple alleles

more than 2 alleles for a single gene can control a trait, blood types, IAIA, IAi, IB

sex chromosomes

last pair of chromosomes-23rd pair, XX and XY, occur more frequently in men

polygenic inheratince

traits are determined by many genes, eye color, skin color, height.

autosome dominate

a single copy of a mutated gene

autosome recessive

two copies of a mutated gene, one from each parent

klinefelters syndrome

male with female characteristics, xxy

turners syndrome

female, no ovaries, sterile, x_ or xo

down syndrome

mental delay, heart defects, 3 # 21

nondisjunction

a failure of chromosomes to separate during meiosis, causes an aneuploid

amniocentesis

inserting a needle into the womb to remove fetal cells for genetic testing

karyotype

a picture of an individuals chromosomes

restriction enzyme

cut DNA into pieces

independant assorsment

describes how different genes are inherited during reproduction

chromosommes located on genes, found in the ribosome

traits are passed from parents to offspring. these traits are determined by