Units 13-16: Inheritance and Genetics

Question 1

Selective Breeding

Answer 1

Process of choosing and breeding specific organisms for particular physical features or behaviors.

Question 2

True Breeding

Answer 2

Organisms that are homozygous for a particular trait or set of traits and produce offspring that exhibit the same characteristics generation after generation.

Question 3

Monohybrid Cross

Answer 3

Cross of two individuals that differ in one trait.

One dude that came from two dudes who are the same in most ways, but different in one big way.

Question 4

Dominant

Answer 4

Describes a trait which always appears (is expressed) in an individual that is either heterozygous (Aa) or homozygous (AA) for that trait.

Question 5

Recessive

Answer 5

Refers to a type of trait which does not appear (is not expressed) in an individual that is heterozygous (Aa) for that trait.

Question 6

Complete Dominance

Answer 6

A condition in which the dominant allele of a gene completely conceals the presence of the recessive allele of a gene; an individual with one recessive and one dominant allele has the same observable physical characteristic as an individual with two dominant alleles.

Question 7

Incomplete Dominance

Answer 7

A condition in which neither of two alleles for the same gene can completely conceal the presence of the other.
ex. wavy hair from a curly hair girl and a straight hair girl

Question 8

Law of Segregation

Answer 8

Mendel’s first law of inheritance, stating that all individuals have two copies of each gene; these copies segregate randomly during gamete formation, and each gamete receives one copy of every gene.

Question 9

Genotype

Answer 9

Combination of alleles.

Question 10

Phenotype

Answer 10

Outward expression of the genotype.

Question 11

Homozgous

Answer 11

Identical alleles for a trait. Ex, RR or rr.

Question 12

Heterozygous

Answer 12

Two different alleles for a trait Rr.

Question 13

Punnett Square

Answer 13

Simple grid used to illustrate all possible combinations of simple genetic crosses.

Question 14

Test Cross

Answer 14

Cross of an individual of unknown genotype with a homozygous recessive individual; used as a method to determine the unknown genotype.

Question 15

Dihybrid Cross

Answer 15

Cross of two individuals that differ in two traits.

Mendel wanted to see if the segregation of one trait would impact another trait

Question 16

Law of Independent Assortment

Answer 16

Mendel’s second law of inheritance, stating that the two alleles for one gene segregate independently of the alleles for other genes during gamete formation.

Question 17

Co-dominance

Answer 17

Describes a situation in which two alleles may be expressed equally; occurs when two different alleles for a trait are both dominant.
Speckled chickens have both black and white feathers.

Question 18

Chromosome Theory Of Inheritance

Answer 18

Theory preposed by Walter Sutton that genes are carried on chromosomes.
Genes exist at specific sites arranged in a linear manner along chromosomes.

Question 19

Linked Genes

Answer 19

Genes found on the same chromosome.

Do not follow the law of independent assortment

Question 20

Crossing Over

Answer 20

The process by which non-sister chromatids exchange genes during prophase I of meiosis, allowing for the recombination of genes.

Question 21

Chromosome Mapping

Answer 21

The process for determining the relative position of genes on a chromosome.

Question 22

Map Unit

Answer 22

The distance between points on a chromosome where a crossover is likely to occur in 1 percent f all meiotic events.
= 1% recombination frequency

Question 23

Recombinant Types (recombinants)

Answer 23

Describes offspring that have a different combination of alleles than the chromosomes of their parents.

Question 24

Parental Types

Answer 24

Describes offspring that have chromosomes that are identical to those of their parents.

Question 25

Map Distance

Answer 25

Distance between genes on a single chromosome. | 1% recombination frequency = 1 map unit

Question 26

Barr Body

Answer 26

Structure formed when the inactive X chromosome condenses tightly.

Question 27

Sex-linked Traits

Answer 27

Trait controlled by genes on either the X or Y chromosome.

Question 28

Barr Body

Answer 28

Structure formed when the inactive X chromosome condenses tightly.

Question 29

Multiple Alleles

Answer 29

A gene with more than two alleles. Order of dominance. Ex. Human blood type, bunny fur colour

Question 30

Order of Dominance

Answer 30

Sequence indicating which alleles are dominant to other alleles.

Question 31

Continuous Traits

Answer 31

Traits for which the phenotypes vary gradually from one extreme to the another and cannot be placed in discrete categories.

Question 32

Polygenic Traits

Answer 32

Traits that are determined by polygenes. Groups of genes that all contribute to the same trait are called polygenes. Dominant genes contribute to the trait, recessive do not.

Question 33

Pedigree

Answer 33

Diagram that uses symbols to illustrate the patterns of relationships and traits among a family over many generations.

Question 34

Genetic Screening

Answer 34

Any of several methods of identifying people who are at risk of developing particular genetic conditions or of passing these conditions on to their children. Ex. Pedigree and blood tests

Question 35

Genetic Counsellor

Answer 35

A person who uses an understanding of genetics to predict and explain traits in children.

Question 36

Marfan Syndrome

Answer 36

Found in chromosome 15; disorder of the connective tissues, causing weakness in the heart, blood vessels, and skeleton, as well as very long limbs. Autosomal dominant.

Question 37

Pangenesis

Answer 37

First theory of inheritance proposed by Aristotle. The egg and the sperm consist of particles, called pangenes. The pangenes are from all parts of the body, and develop into all parts of the body.

Question 38

Heterozygote Advantage

Answer 38

Heterozygous individuals have an advantage over homozygous dominant or homozygous recessive. Having sickle cell trait can create a resistance to malaria.

Question 39

Pedigree Analysis of Recessive Genes

Answer 39

Two unaffected individuals with an affected child.

Question 40

Pedigree Analysis of Dominant Genes

Answer 40

Every affected individual with a parent that is also affected. Two affected individuals have an unaffected child.

Question 41

Pedigree Analysis of X-linked Genes

Answer 41

X-linked recessive: More men. | X-linked dominant: More women.