objective 10 pt 2 Flashcards
study of mechanism of heredity
genetics
who was basic principles of genetics proposed by and when?
Mendel in mid 1800s
segments of DNA, contain the “recipe” or blueprints, for synthesis of proteins
genes
how many chromosomes do cells contain?
46
have 23 because these cells replicate but undergo 2 cell divisions
sex cells
- Each chromosome assorts itself independently
during meiosis - Also during one phase of meiosis, chromosomes
exchange genes - So each sperm & each ovum is likely to have a different
set of 23 chromosomes - Each child from the same set of parents is very
likely to be genetically unique
meiosis
may be expressed differently among individual offspring
each trait is controlled by 2 sets of similar genes, one from each parent
genetic units
alleles are same for single trait
homozygous
alleles are different for single trait
heterozygous
one allele masks (suppresses) expression of its recessive partner
dominance
is donoted by capital letter and recessive by same letter but in lowercase
dominant allele
is expressed even if other allele codes for recessive trait
dominant trait
expressed only if both alleles are recessive
recessive trait
genetic makeup of a person for a trait
genotype
physical expression of genotype
phenotype
- only one allele is required for the trait to be observed.
- A dominant allele will mask a recessive allele
- A dominant allele is denoted by a capital letter
dominant-recessive inheritance
genes that exhibit more than 2 allele forms
multiple allele inheritance
- Inherited traits determined by genes on sex
chromosomes - X chromosome from mother
- Y chromosome from father
- Female XX
- Male XY
sex-linked inheritance
what are the 3 events that each person is genetically unique from?
independent assortment
crossover
random fertilization
what are the 2 impt seperations of traits that occur in meiosis 1 of gametogenesis>
segregation
independent assortment
two alleles of one particular trait will be
separated and distributed to two different daughter cells
segregation
alleles of two different traits on two
different chromosomes are distributed independently of each
other
independent assortment
Single egg is fertilized by a single sperm in a
random manner
* Independent assortment and random fertilization
together result in ~72 trillion zygote possibilities
* Egg possibilities sperm possibilities = 8.5 million 8.5
million = ~72 trillion
* Additional variations introduced by crossover
would increase this number of possibilities
exponentially
* The odds that you are who you are were greater than 1
in >72,000,000,000
random fertilization
