m1 + 2 lect. - genetics Flashcards
what is an autosome?
the 22 chromosomes besides the sex pair
(define us as human)
what are sex chromosomes?
XX or XY
(define us as female or male)
what are genotypes?
our specific genetic makeup (3 billion base pairs)
all of the genes => proteins => traits
what are phenotypes?
physical expression of genotype
types of inheritance?
dominant or recessive
combinations of dominant or recessive with allele pairs?
DD - homozygous dominant
Dr - heterozygous dominant
rr - homozygous recessive
dominant traits are:
always expressed even if heterozygous
recessive traits are:
only expressed if homozygous
(essay Q) incomplete dominance is:
when heterozygous individuals will express both traits
(recessive trait will be expressed in varying degrees)
ex.) sickle cell trait - can be treated
sickle cell anemia - results in death
achondroplasia - DD - death
Dr - dwarfism
rr - normal growth
multiple allele inheritance is:
when the individual inherits more than one pair of alleles ( more than one dominant trait can be expressed)
ex.) blood typing
A + B are co-dominant
O is a homozygous recessive
polygene inheritance is:
traits controlled by more than one or two pairs of genes (continuous variance between offspring)
ex.) skin color, height, metabolism, hair color
(essay Q) sex - linked inheritance
inheritance occurring only on the sex hormones
Y-gene is about 1/3 of the size of X
(called Y-linked)
X carries genes that may be expressed even if recessive
(called X-linked)
non-disjunction
- occurs in gametogenesis
- there is uncomplete separation of the chromosomes in M2
- more common in female over age of 40
examples of non-disjunction:
trisomy
- 18, 21, superfemale, supermale
monosomy
- turner’s
- kleinfelter’s
what are mutations?
change in the DNA of an organism which could be passed down to the offspring
causes: teratogens - free radicals
additions and deletions to DNA
