Chapter 3 Exam Flashcards
what is a test cross
Crossing a plant with an unknown genotype (PP or Pp) with a known genotype (pp)
what is a polygenic trait
A single trait that is controlled by more than one gene (poly/many genes) color of skin, eyes, and many more things
what does it mean to have multiple alleles
A trait that has more than two different versions (blood type- A,B, AB, and O)
what is meiosis
type of cell division in which the number of chromosomes is reduced by half and four haploid cells are produced(gametes).
True or false: When gametes (haploid cells) combine in fertilization, the offspring (diploid cells) will have two of each chromosome.
true
what does diploid mean
contains 2 sets of chromosomes
what does haploid mean
contain a single set of chromosomes
what is the difference between somatic cells and gametes
somatic cells are also called body cells, and gametes are only sperm cells and egg cells.
what are homologous chromosomes
(same size, shape, centromere location, and genes…but NOT exact copies because of different versions of the genes)-
what does homozygous mean
two identical allele for a gene (TT) or (tt)
what does heterozygous mean
two different alleles for a particular gene (Tt)
what is genotype
The combination of alleles (Tt) or (tt)
what is a phenotype
The expression of alleles (tall) or (short)
what is true about dominant and recessive traits
There are two factors that control a characteristic. Dominant trait(represented by a capital letter) dominates the recessive allele(represented by a lowercase letter) so the dominant allele shows through.
monohybrid vs. dihybrid cross
monohybrid cross is considering only one trait, and usually refers to crossing individuals with opposing traits (ex. Flower color - purple x white). Dihybrid cross is considering two traits at one time (ex. Flower color and seed color)
what are autosomal chromosomes
22 pairs in humans that contain genes for characteristics, unrelated to sex.
what are sex chromosomes
one of two chromosomes (in humans, X or Y chromosome) that determine the sex of an individual in a sexually reproducing species.
what is pharmacogenomics
the study of how someone will react to medicines
what made Mendel’s experiments different from Knights
Mendel kept track of the results he got from his crosses. He documented the results and did some basic math (ratios) to analyze the offspring produced.
why were pea plants good for early studies
Fast growing
Easy to propagate
Visible characteristics
Variable characteristics
Two versions of each trait
what is a monohybrid cross
A genetic cross between two individuals only concerning one trait. 2x2 square. The purpose of a monohybrid cross is to study how one specific trait is inherited from one generation to the next.
what is a dihybrid cross
a genetic cross that examines the inheritance of two different traits. 4x4 square
What genetic material is received from father, and what is received from mother?
Each parent contributes ½ of the genome of the new individual.
what is the law of segregation
Mendel’s first law of inheritance that states that the two factors (alleles) that control a given trait separate and go to different gametes.
what is the law of independent assortment
Mendel’s second law of inheritance that states that factors (alleles) controlling different traits are inherited independently of each other.
know how to do a punnett square along with probability
what does punnet square help to do?
chart for determining the expected ratios of different genotypes in the offspring of two parents.
what do punnett squares show
All of the possible offspring that can result from a given cross.
find the ratios
Tt x Tt , TT x tt, Tt x TT
Tt x Tt = genotypic ratio of TT:Tt:tt is 1:2:1, phenotypic ratio is Tall:short is 3:1
Number of chromosomes in body cell vs gametes
46 body cell and 23 gamete
Diploid cell vs Haploid cell type- These cells have two complete sets of chromosomes.
Diploid- In humans, diploid cells have 46 chromosomes (23 pairs).
Most body cells (like skin, muscle, and brain cells) are diploid.
Haploid- These cells have only one set of chromosomes.
In humans, haploid cells have 23 chromosomes.
Gametes (sperm and egg cells) are haploid.
what are sex linked traits
Sex-linked traits/genes are usually found on the X-chromosome (the Y-chromosome only has a few genes). An X-linked trait is more common in men than women because they only have one X chromosome. Women have two chances to get the dominant allele and will not suffer the disorder.
what are autosomal traits
Traits/genes found on chromosomes #1-22.
what is true about autosomal disorders and sex linked disorders carriers?
Autosomal disorder carriers can be male or female
Sex linked disorder carriers are always unaffected females
TT x tt
Tt x Tx
Tt x tt
RR x WW (incomplete dominance)
IAIA X IBi (codominance)
Tall
Tall:short
Tall:short
Pink (different than Red and White)
Type A:Type AB
what are the possible gamete combinations
RRSs =
RrSs =
Rrss =
RRSs = RS and Rs
RrSs = RS, Rs, rS, and rs
Rrss = Rs and rs
what is codominance
relationship between two alleles for the same gene in which both alleles are expressed equally in the phenotype of the heterozygote. (Both alleles will express equally)
what is incomplete dominance
relationship between the alleles for a gene in which one allele is only partly dominant to the other allele so an intermediate phenotype results (Neither allele is dominant so something different will be the phenotype)
what is a polygenic trait
characteristic, or trait, controlled by more than two genes(eye color)
what are multiple allele traits
traits that are controlled by a single gene with more than two alleles(blood type).
karyotypes uses and limitations
(used to see major chromosomal abnormalities in the offspring like Down’s Syndrome, missing or damaged chromosomes. Does NOT show specific traits because you cannot see the specific genes, just the chromosomes)
Examples of chromosomal abnormalities
Down’s Syndrome - extra 21st chromosomes
Turner’s Syndrome - missing and X chromosomes
Klinefelter’s Syndrome - extra X in men
what is a pedigree
chart showing how a trait is passed from generation to generation within a family.
what do circles stand for in a pedigree
female
what do squares stand for in a pedigree
male
what does a half colored circle and half not colored circle represent
the female is a carrier of the disease but is not affected
what are the environmental impacts on phenotype
Nutrition level
pH of soil
Temperature
Amount of sunlight
How have we used cloning technology?
Used to clone Genes for research or gene therapy
Steps of cloning
Steps: Isolation(cut DNA), Ligation(combine to plasmid), Transformation(into bacteria), Selection(find successful bacteria)
what does polymerase chain reaction do
PCR makes many copies of a segment of DNA for study
what are the three steps of PCR
Denaturing
Annealing
Extension
what happens in denaturing
Denaturing: heating to open the strand
what happens in annealing
Annealing: cooling DNA to allow primer to bond
what happens in extention
Extension: Taq polymerase adds nucleotides
what do heating and cooling cycles do
Precise heating and cooling cycles increase the overall quality of DNA.
