Unit 6- Classical Genetics Flashcards
Trait
A variation of a particular genetic or characteristic
Who is Gregor Mendel?
An Austrian monk who found the basic rules of inheritance through a series of expirements
Blending hypothesis
Hypothesis in 1800’s explaining how offspring inherited traits from both parents
Genetics
The study of heredity
What did Mendel do for his work?
He bread pea plants and studied inheritance patterns for 7 years
Mendel’s hypothesis
Parents pass off separate and distinct “factors” to their offspring
(Factors are known as genes now)
Cross fertilization
The name of the process Mendel used to cross two true breeding plants with two contrasting traits
Alleles
Alternate forms of genes
Dominant allele
An allele in a heterozygous individual that appears to affect the trait
Recessive allele
A allele in a heterozygous individual that appears to not affect the trait
Homozygous
An individual that has two alleles for a character that is the same
Heterozygous
An individual that have two alleles for a character that are different
Mendel’s principle of segregation
The two alleles for a character segregate (separate) during the formation of gametes (sex cells), so that each gamete carries only one allele for each character.
Mendel’s Principle of Independent Assortment
during gamete formation in an F2 cross, a particular allele for one character can be paired with either allele of another character.
gametes are sorted independently
monohybrid cross
mating of two organisms that differ in only one character
dihybrid cross
mating of two organisms that differ in two characters
hybrid
offspring of two different true-breeding varieties
Punnett square
diagram showing the probabilities of the possible outcomes of a genetic cross
phenotype
observable traits of an organism
genotype
genetic makeup of an organism; an organism’s combination of alleles
testcross
mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual
intermediate inheritance
inheritance in which heterozygotes have a phenotype intermediate between the phenotypes of the two homozygotes
(blue chicken)
codominance
inheritance pattern in which a heterozygote expresses the distinct traits of both alleles
(blood type)
polygenic inheritance
combined effect of two or more genes on a single character
height, hair color, &more
environmental influences
Phenotype changes due to environment but the genotype can never change due to environment.
chromosome theory of inheritance
generalization that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance pattern
gene locus
specific location of a gene on a chromosome
crossing over
crossing over during meiosis sorts different genes and split up genes
genetic linkage
tendency for alleles of genes on the same chromosome to be inherited together
the closer the genes are, the greater the genetic linkage
sex-linked gene
gene located on a sex chromosome
Sex-linked Disorder
mostly in men because the trait is reccessive and men only need one of the traits to receive the disorder
(more common on Xchromosome because it is bigger than the Y chromosome)
genome
complete set of an organism’s genetic material
histone
small protein that DNA wraps around
dna coils around the histone, then the coil coils, then over and over again until it fits into the chromosome
The Human Genome Project
completely sequencing the human genome
(from 1990-2000)
nondisjunction
event during meiosis in which homologous chromosomes or sister chromatids fail to separate
trisomy 21
condition in which an individual has three number 21 chromosomes, resulting in Down syndrome
duplication
change to a chromosome in which part of the chromosome is repeated
deletion
change to a chromosome in which a fragment of the chromosome is removed
inversion
change to a chromosome in which a fragment of the original chromosome is reversed
translocation
change to a chromosome in which a fragment of one chromosome attaches to a nonhomologous chromosome
transposon
genetic element that moves from one location to another in a genome
pedigree
family tree that records and traces the occurrence of a trait in a family
carrier
individual who has one copy of the allele for a recessive disorder and does not exhibit symptoms
growth factor
protein that initiates cell division
tumor-suppressor gene
gene that codes for a protein that stops cell division in particular situations
oncogene
cancer-causing gene
inherited cancer
mutated version of a tumor-suppressor gene
