Mendelian Genetics Study Guide

Explain each of Mendel’s law. How is each law used in Punnett Squares? Law of…. 1.Independent Assortment: alleles sort randomly and independently of each other (seen in dihybrid Punnett squares) 2.Segregation: paired alleles for a trait separate when gametes are formed (why sperm and egg only carry one allele for a trait, not a pair) 3.Unit Characters: units in a cell are responsible for traits (genes), and these units come in pairs otherwise known as alleles (an early explanation of genes)

Compare and contrast mitosis and meiosis. 2 identical diploid daughter cells produced 4 haploid daughter cells produced one duplication of DNA, one cell division one duplication of DNA, two cell divisions a form a asexual reproduction 1st stage in sexual reproduction

How are human egg cells similar to human sperm cells? both are haploid

combinations different from those of either parent How many chromosomes does a cell have after meiosis (as compared to a parent cell)? ½ the number with gene combinations different from those of either parent

What is the F1 and F2 generation? F1 generation is the offspring of the P generation (true-breeding) F2 generation is a result of the crossing of two F1 hybrids

Describe and give an example of polygenic traits. traits controlled by multiple genes; ex> skin color

What happens during oogenesis in humans? Meiosis in females that produces 3 inactive polar bodies and one egg cell

Define and give an example of incomplete dominance and codominance. Incomplete dominance: one allele not completely dominant over another; heterozygous phenotype lies between the two homozygous phenotypes; 2 alleles produce 3 phenotypes; Example: red, white, and pink or straight, curly, and wavy hair Co-dominance: both phenotypes produced by different alleles are expressed; ex> the allele for black feathers is codominant with the allele for white feathers; heterozygous chickens are speckled with black and white feathers.

Define phenotype and genotype. Genotype: allele combination for a particular trait in an organism Phenotype: The physical appearance for a particular trait in an organism

What is the diploid number of chromosomes in a human cell? 46

A sex cell (sperm cell or egg cell) Define gamete. A sex cell (sperm cell or egg cell)

Define zygote. Single cell formed when the egg and sperm cell unite during fertilization

If an organism has 20 chromosomes for his normal diploid number, then how many chromosomes will it have after meiosis? 10

Describe the process of fertilization. Sperm cell and egg cell unite to form a zygote

How are identical twins formed? One sperm cell fertilizes one egg cell and the zygote then splits in half.

What alleles represent homozygous dominant tall. Heterozygous tall What alleles represent homozygous dominant tall? Heterozygous tall? Homozygous recessive short? TT Tt tt

What happens in the process of “crossing over?” chromatids of the homologous chromosomes cross over one another and the crossed sections of the chromatids exchange

Define Heredity: A set of characteristics passed from parent to offspring

What did Mendel work when studying heredity? Why did he use these? mathematical analysis of the offspring of pea plants; small, could produce large amounts of offspring in short amount of time

What did Mendel discover from his test crosses? Mendel was able to develop his laws that described inheritance: law of independent assortment, law of segregation, and the law of unit characters

What is the difference between self-pollination and cross pollination? Self-pollination: Pollen from a flower fertilizes an egg cell on the same flower; offspring have a single parent. Cross-pollination: Pollen from one plant fertilizes eggs from another plant; offspring have 2 different parents

Complete a monohybrid cross for the following examples Complete a monohybrid cross for the following examples. Give the phenotype and genotype. In squirrels, the gene for gray fur (G) is dominant over the gene for black fur (g). Cross a heterozygous squirrel with a black fur squirrel . What percentage of the off-spring will have black fur? 50% G g g gg

In squirrels, the gene for gray fur (G) is dominant over the gene for black fur (g). Cross a heterozygous squirrel with a heterozygous squirrel . What percentage of the off-spring will have gray fur? 75% G g G g GG Gg

In squirrels, the gene for gray fur (G) is dominant over the gene for black fur (g). Cross a homozygous dominant squirrel with a black fur squirrel . What percentage of the off-spring will have black fur? 0% G G g Gg

Genotype: 4SSRR, 4SsRR, 4 SsRR, 4 SsRr In tomatoes, the texture and color of the skin matter a great deal. The smooth texture (S) is dominant to the peachy texture (s) and the red color (R) is dominant to yellow ( r ). Complete a dihybrid cross between two tomatoes. One tomato is SSRR. The other is SsRr. Determine the phenotype and genotype of your dihybrid cross. SR Sr sR sr SR Genotype: 4SSRR, 4SsRR, 4 SsRR, 4 SsRr Phenotype: all smooth texture/red color SSRR SSRr SsRR SsRr

What happens to the diploid number of chromosomes that an organism has after it undergoes meiosis? It is cut in half

What is the chromosome arrangement for the picture above? (n + n  2n) Fertilization

The diploid number of chromosomes for a human cell is ­­­­­­­____? 46

Complex organisms produce gametes (egg and sperm) that unite during fertilization, forming a single cell known as _______. Zygote

Which of Mendel’s laws in shown in the picture above? segregation

The picture above demonstrates what concept? fertilization

The picture above demonstrates what concept? Crossing-over

The picture shown above demonstrates what concept? meiosis