Lab 5

Question 1

Metacentric

Answer 1

The centromere in located in the middle of the chromosome

Question 2

Subterminal

Answer 2

The centromere is located between the middle and the end of the chromosome

Question 3

Acrocentric

Answer 3

The centromere is located very close to one end of the chromosome

Question 4

Autosomal chromosomes

Answer 4

Carry genes that affect somatic characteristics (such as hair colour)

Question 5

Sex chromosomes

Answer 5

Responsible for determining the genetic sex of an individual.

X or Y

Females: XX
Males: XY

Question 6

Karyotype

Answer 6

A laboratory-produced image that arranges the chromosomes into pairs according to size and centromere position.

It is usually prepared from a cell during mitosis metaphase.

Question 7

Why is it necessary to prepare a karyotype?

Answer 7

In order to look for any abnormalities in chromosome number or structure.

Question 8

Nondisjunction

Answer 8

The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division.

Question 9

Down syndrome

Answer 9

(aka Trisomy 21)

A genetic disorder where an individual has 3 copies of chromosome 21, rather than the usual 2 copies. It happens when the chromosomes fail to separate properly during meiosis.

Question 10

Patau syndrome

Answer 10

(aka Trisomy 13)

A genetic disorder in which there are 3 copies rather than 2 of chromosome 13 in either the egg or sperm before conception.

Question 11

Edwards symdrome

Answer 11

(aka trisomy 18)

A genetic disorder in which an individual has 3 copies of chromosome 18 rather than 2.

Question 12

Turner’s syndrome

Answer 12

A genetic disorder in which a female only has 1 X chromosome rather than 2.

Question 13

Klinefelter’s syndrome

Answer 13

A genetic condition in which a male is born with an extra X chromosome, resulting in XXY.

Question 14

Cri-du-chat syndrome

Answer 14

A genetic disorder in which there is total or partial loss chromosome 5

Question 15

Locus

Answer 15

The position of a gene on a chromosome

(Drawn as a small stripe on a chromatid)

Question 16

Genotype

Answer 16

The genetic constitution of an organism.

It is the actual genes present on the chromosomes of an individual

Uses: AA, Aa , aa

Question 17

Phenotype

Answer 17

The actual observed characteristics of an individual.

Is it the physical expression of a gene

Ex. Blue eyes, brown hair…etc.

Question 18

Alleles

Answer 18

Alternate forms of the same gene (ex. A and a) found at the same locus on a homologous chromosomes.

This codes for different phenotypes.

Question 19

Dominant allele

Answer 19

An allele which needs to be present on only one of the two homologous chromosomes in order to be expressed.

Expressed by the capital letter (ex. A)

AA and Aa are phenotypically identical e since the dominant A masks the alternate allele a.

Question 20

Recessive allele

Answer 20

An allele which must be present on both members of a pair of homologous chromosomes in order to be phenotypically expressed. (aa)

Expressed by lowercase letter (ex. a)

Question 21

Homozygous

Answer 21

Refers to the presence of identical alleles on homologous chromosomes.

i.e. AA or aa

Question 22

Heterozygous

Answer 22

Refers to the presence of unlike alleles on homologous chromosomes.

i.e. Aa

Question 23

First filial generation (F1)

Answer 23

The offspring resulting from the crossing of individuals of the parental generation.

Question 24

Second filial generation (F2)

Answer 24

The offspring resulting from crossing members of the F1 generation among themselves.

Question 25

Monohybrid cross

Answer 25

Examines the inheritance of a single trait.

Ex. AA

Question 26

Dihybrid cross

Answer 26

Examines the inheritance of 2 different traits located on 2 different pairs of homologous chromosomes.

Ex. AaBb