Unit 8: Meiosis and Genetics

Question 1

meiosis

Answer 1

the process by which sex cells divide to create eggs and sperm

Question 2

fertilization

Answer 2

when a sperm and egg combine

Question 3

gametes

Answer 3

sex cells, eggs and sperm, the cells after meiosis II

Question 4

ovaries and eggs

Answer 4

female reproductive organs and gametes, eggs come from ovaries

Question 5

testes and sperm

Answer 5

male reproductive organs and gametes, sperm come from testes

Question 6

zygote

Answer 6

a fertilized egg, the earliest stage of development of a new organism

Question 7

embryo

Answer 7

a new organism in development

Question 8

homologous chromosomes

Answer 8

chromosomes that carry the same genes (even if different alleles), pair up and divide in meiosis I

Question 9

autosomes

Answer 9

normal chromosomes (non-sex chromosomes)

Question 10

sex chromosomes

Answer 10

chromosomes that are linked to an individuals biological sex, X or Y, females typically have XX and males typically have XY

Question 11

haploid

Answer 11

cells that only have half of their original genes, all cells produced by meiosis (when done correctly) are haploid, written as N

Question 12

diploid

Answer 12

cells that have their original number of chromosomes, all cells produced by mitosis are diploid, as well as cells that go into meiosis, written as 2N

Question 13

crossing-over

Answer 13

In prophase I, chromosomes cross over each other and exchange some of their genes

Question 14

karyotype

Answer 14

A visual representation of an individual’s chromosomes

Question 15

nondisjunction

Answer 15

when an error occurs in meiosis so that chromosome do not split properly

Question 16

polar body

Answer 16

the smaller of 2 cells produced at the end of meiosis II in females, polar body degenerates, the other cell is larger and can go on to be fertilized

Question 17

x-inactivation

Answer 17

in people with two x chromosomes, one of them becomes inactivated so two of the same chromosome are not trying to “work” at the same time

Question 18

Barr body

Answer 18

the inactivated x chromosome condenses into a Barr body which is stored inside the cell

Question 19

trait

Answer 19

a characteristic of an individual, such as eye color (eyes can be blue, brown, green, etc.)

Question 20

gene

Answer 20

a part of a chromosome that codes for trait (ex: eye color)

Question 21

alleles

Answer 21

the variant of a gene that codes for the same trait but different characteristic (ex: blue eyes)

Question 22

genotype

Answer 22

the genes an individual has

Question 23

phenotype

Answer 23

the physical characteristics an individual has (based on their genotype)

Question 24

homozygous

Answer 24

having 2 of the same allele (either 2 dominant or 2 recessive)

Question 25

heterozygous

Answer 25

having 2 different alleles (one dominant and one recessive)

Question 26

monohybrid

Answer 26

a cross of individuals that vary on one trait

Question 27

dihybrid

Answer 27

a cross of individuals that vary in two traits

Question 28

Gregor Mendel

Answer 28

The scientist who discovered the basic principles of inheritance through his work breeding pea plants

Question 29

law of segregation

Answer 29

alleles separate randomly into gametes

Question 30

law of independent assortment

Answer 30

allows for 4 possible gametes with combinations of traits that are different from the parents

Question 31

pedigree chart

Answer 31

a diagram that represents the inheritance of certain traits or genes through families over generations

Question 32

punnett square

Answer 32

diagrams used to find the probabilities that offspring will have certain genotypes (which can determine phenotype)

Question 33

recessive

Answer 33

to express a recessive trait, an individual needs both recessive alleles

Question 34

dominant

Answer 34

to expressive a dominant trait, an individual only needs one dominant allele (can have 2)

Question 35

carrier

Answer 35

a female who has the gene for a certain condition hidden in a recessive gene (because women have 2 X chromosomes, a heterozygous female would not express it)

Question 36

purebred (true-breeding)

Answer 36

an individual with two identical alleles, homozygous

Question 37

incomplete dominance

Answer 37

when one trait does not completely hide the other trait, a blended phenotype is expressed

Question 38

codominance

Answer 38

there is more than 1 dominant allele, a heterozygous individual expresses both (think different color spots on fur)

Question 39

sex-linked

Answer 39

traits that are determined by genes found on sex chromosomes (X or Y), usually the X chromosome

Question 40

polyallelic (multiple alleles)

Answer 40

occurs when a gene has more than two versions, leading to multiple phenotypes (think human blood type)

Question 41

polygenic

Answer 41

traits that are determined by a combination of genes