Mendelian Genetics

Question 1

Pure breeding line

Answer 1

population that breeds true for a particular trait.

Question 2

Hybrid

Answer 2

plants/animals generated from crossing two pure breeding lines.

Question 3

Phenotype

Answer 3

physical or measurable appearance of a trait.

Question 4

Gene

Answer 4

unit of heredity, residing at a specific point on a chromosome; a length of DNA that specifies a product

Question 5

Allele

Answer 5

the variant of a specific gene. An individual inherits two alleles, one from each parent, for any given genomic location where such variation exists.

Question 6

Genotype

Answer 6

the specific allelic combination for a certain gene or set of genes

Question 7

Gamete

Answer 7

They are also referred to as sex cells. Female gametes are called ova or egg cells, and male gametes are called sperm. Gametes are haploid cells, and each cell carries only one copy of each chromosome.

Question 8

Segregation

Answer 8

separation of parental homologous chromosomes at meiosis and the consequent separation of alleles and their distribution to different gametes

Question 9

Dominant

Answer 9

the allele that expresses itself at the expense of an alternate allele; the phenotype that is expressed in the F1 generation from the cross of two pure lines

Question 10

an allele whose expression is suppressed in the presence of a dominant allele; the phenotype that disappears in the F1 generation from the cross of two pure lines and reappears in the F2 generation

Answer 10

Recessive

Question 11

Homozygous

Answer 11

an individual which contains only one allele type at the allelic pair; for example DD is homozygous dominant and dd is homozygous recessive

Question 12

Heterozygous

Answer 12

an individual that contains two different alleles at the allelic pair; for example Dd heterozygote rather than DD or dd homozygote.

Question 13

hybrid offspring of parents differing in one character => heterozygous for a single pair of alleles. 3:1

Answer 13

Monohybrid

Question 14

hybrid offspring of parents differing in two distinct characters => heterozygous for two pairs of alleles. 9:3:3:1

Answer 14

Dihybrid

Question 15

The Law of Independent Assortment:

Answer 15

During gamete formation one pair of factors (alleles) for one trait segregates independently of the alleles for a second trait.

Question 16

a descendant or the descendants of a person, animal, or plant; offspring

Answer 16

.progeny

Question 17

use of multiplication in a question about probability

Answer 17

probability of y multiplied by the probability of x = total probability. use when questions contain an ‘and’

Question 18

use of addition in a question regarding genetic probability.

Answer 18

probability of y + the probability of x = total probability when answer questions with ‘or’ in them. (example: what is the probability of flipping a coin for hads or tails= 0.5 + 0.5 = 1)

Question 19

Pedigree analysis

Answer 19

monitoring the inheritance of genes over many generations within a family it is possible to deduce how certain genes are inherited.

Question 20

Autosomal traits

Answer 20

are those for which genes are present on the autosomes (non sex chromosomes).

Question 21

Autosomal recessive traits are characterised by:

Answer 21

Progeny that display the phenotype arising from parents that do not display the phenotype

Question 22

Autosomal dominant traits are characterised by:

Answer 22

Individuals displaying the phenotype MUST have had at least one parent displaying the phenotype;
The phenotype generally appears every in every generation;
The phenotype appears in males and females equally.

Question 23

Pedigree methods in plant breeding are applied when:

Answer 23

• Handling segregating traits from crosses in self pollinated crops, or when self-pollination can be forced;
• Improving traits that are quick and easy to measure disease resistance, plant height, time to maturity;
• Improvement in an established variety for some specific character is required.

Question 24

New alleles arise via

Answer 24

mutation

Question 25

The Central Dogma

Answer 25

Genes make Proteins. is an explanation of the flow of genetic information within a biological system. It is often stated as “DNA makes RNA, and RNA makes protein”,

Question 26

In essence one gene may affect or mask the effects of others and this phenomenon is termed

Answer 26

epistasis, The defective gene is said to be epistatic to the functional gene and the gene or locus, which is masked, is termed hypostatic. in some cases of epistasis, one gene depends on the other for it to be expressed.

Question 27

the difference between epistasis and dominance

Answer 27

Dominance = intra-allelic suppression
Epistasis = inter-allelic suppression

Question 28

incomplete dominance

Answer 28

non-mendillan trait: a hybrid of a phenotype is shown, such as apurple flower produced by crossing a white and red flower.

Question 29

co-dominance

Answer 29

non-mendillan trait: both traits show up in the phenotype. speckled chickens.

Question 30

polygenic traits

Answer 30

multiple genes that determine the phenotype. such as heiht or skin colour.

Question 31

a gamete contains one half the amount of …….? than a diploid cell.

Answer 31

chromosomes