Exam 4: Genetics and Meiosis

Question 1

Genetics

Answer 1

The scientific study of heredity and variation. We don’t inherit traits, but rather genes.

Question 2

Mitosis

Answer 2

Asexual reproduction resulting in genetically identical offspring

Question 3

Meiosis

Answer 3

Sexual reproduction forming gametes. The process by which those gametes become haploid instead of diploid.

Question 4

Genes

Answer 4

Segments of DNA on chromosomes.
One set of chromosomes is inherited from each parent.

Question 5

Gametes

Answer 5

Reproductive cells. They are haploid, there are 23, and contain chromosomes 1-22 and a single sex chromosome. Eggs: sex chromosome is X. Sperm: sex chromosome is X or Y. They are the only types of human cells produced by meiosis.

Question 6

Fertilization

Answer 6

The fusion of two gametes forms a diploid zygote.

Question 7

Somatic cell

Answer 7

Body cell. Anything in humans that is not a gamete.

Question 8

Important elements of meiosis

Answer 8

In the first cell division (meiosis I), homologous chromosomes separate, resulting in two haploid daughter cells with replicated chromosomes. In the second cell division (meiosis II), sister chromatids separate, resulting in four haploid daughter cells with replicated chromosomes.

Question 9

Variation in a population

Answer 9

Prerequisite for evolution. Sexual reproduction contributes to this.

Question 10

Natural selection

Answer 10

Accumulation of genetic variations favored by the environment

Question 11

Mutation

Answer 11

Change in the nucleotide sequence of DNA, which creates alternative alleles of a gene.

Question 12

Genotype

Answer 12

Which alleles an individual has: homozygous (2 of the same alleles), or heterozygous (2 different alleles)

Question 13

Phenotype

Answer 13

The physical characteristics of an organism

Question 14

Dominant vs recessive alleles

Answer 14

Dominant designated by capital letter, recessive by lowercase. Otherwise explanation is in the name itself. Saying an allele is dominant doesn’t mean it’s common. It means it masks a recessive allele in heterozygotes.

Question 15

Law of segregation

Answer 15

Mendel’s reasoning that patterns of inheritance included: individuals have two alleles. And those separate from one another during gamete formation.

Question 16

Homozygous

Answer 16

Both alleles are the same. Must specify homozygous dominant vs recessive.

Question 17

Carrier

Answer 17

Individuals who are heterozygous for a particular gene of interest and thus can pass on the recessive allele without showing any of its effects.

Question 18

Complications to Mendelian patterns of inheritance—why

Answer 18

-not all traits have only two possibilities
-not all traits are controlled by a single gene
-not all alleles are clearly dominant or recessive

Question 19

Mendelian traits

Answer 19

When phenotypes of the heterozygote and dominant homozygous are identical

Question 20

Incomplete dominance

Answer 20

The phenotype of the heyerozygote is intermediate

Question 21

Codominance

Answer 21

Both phenotypes are expressed by the heterozygote

Question 22

Pleiotropy

Answer 22

One gene with many phenotypic effects. Example is albinism.

Question 23

Polygenic traits

Answer 23

A single trait whose phenotype is determined by the interaction between alleles of more than one gene

Question 24

Sex-linked genes

Answer 24

Genes located on either sex chromosome. Usually the X. Examples: color blindness, hemophilia