genetics and inheritance

Question 1

locus

Answer 1

the exact position (location) of a gene on a chromosome

Question 2

filial generation (F1)

Answer 2

offspring of parent organisms

Question 3

gene

Answer 3

a segment of DNA in
a chromosome that codes for
a particular
characteristic

Question 4

alleles

Answer 4

2 alternative forms of a gene at the same locus

Question 5

genotype

Answer 5

The total genetic composition of an organism.
It’s the info present in the gene alleles

Eg, BB, Bb, or bb

Question 6

phenotype

Answer 6

the physical
appearance of an
organism based on
the genotype, e.g. tall,
short

Question 7

dominant
allele

Answer 7

An allele that masks or suppresses the expression of the allele partner on the chromosome pair and the dominant characteristic is seen in the homozygous (eg, TT) and heterozygous state (eg, Tt) in the phenotype

Question 8

recessive
allele

Answer 8

An allele that is suppressed when the allele partner is dominant. The recessive trait will only be expressed/seen if both alleles for the trait are homozygous recessive e.g.: tt

Question 9

heterozygous

Answer 9

An individual having two non-identical alleles for a characteristic

Question 10

homozygous

Answer 10

When two alleles that control a single trait (on the same locus) are identical.

Question 11

monohybrid
cross

Answer 11

a genetic cross involving one characteristic eg colour of seeds

Question 12

dihybrid cross

Answer 12

a genetic cross involving 2 diff characteristics eg shape and colour of seeds

Question 13

complete
dominance

Answer 13

a type of inheritance
where the
dominant allele
masks the
expression of a
recessive allele
in the heterozygous condition

Question 14

incomplete
dominance

Answer 14

the type of inheritance where both alleles express themselves in such a way that an intermediate phenotype is formed

eg, a white flowering plant crossed with a red flowering plant will produce a pink flowering plant

Question 15

co-dominance

Answer 15

the type of inheritance where both alleles are equally dom and both express themselves equally in the phenotype

eg, a white cow crossed with a red bull will produce a calf with red and white patches

Question 16

multiple
alleles

Answer 16

when there are more than 2 possible alleles for one gene locus

eg, blood groups

Question 17

karyotype

Answer 17

the number,
shape and
arrangement of
the
chromosomes
in the nucleus
of a somatic
cell

Question 18

cloning

Answer 18

process by which
genetically identical
organisms are formed
using biotechnology

Question 19

genetic
modification

Answer 19

manipulation of the
genetic material of
an organism to get
desired changes

Question 20

human
genome

Answer 20

mapping of the exact
position of all the
genes in all the
chromosomes of a
human

Question 21

homologous
pair of
chromosomes

Answer 21

a set of one maternal and one paternal chromosome that pair up
with each other inside a cell during meiosis – homologous
chromosomes are the same size and shape, and carry the same
or similar alleles

Question 22

Mendel’s First Law of Inheritance: Law (principle) of Segregation

Answer 22

the 2 alleles for each gene are placed in diff gametes

Question 23

Mendel’s Second Law of Inheritance: Law of Dominance

Answer 23

when 2 alleles of an inherited pair is heterozygous, then the allele that is expressed in the phenotype is dominant whereas the allele not expressed is recessive

Question 24

Mendel’s Third Law of Inheritance: Law (principle) of Independent
Assortment

Answer 24

the alleles of 2 (or more) different genes get sorted into gametes independently of one another

Question 25

albinism

Answer 25

the condition that results from the absence of skin pigmentation

Question 26

artificial selection/ selective breading

Answer 26

the breading of organisms over many generations to achieve a desirable phenotype

Question 27

biotechnology

Answer 27

the use of biological processes, organisms or systems to improve the quality of human life

Question 28

clone

Answer 28

a copy of an organism that is genetically identical to the original organism

Question 29

chromatin network

Answer 29

visible as thread-like structures in the nucleus of an inactive cell

Question 30

chromosome

Answer 30

a structure made up of 2 chromatids joined by a centromere that carries the hereditary characteristics within the DNA

Question 31

gene mutation

Answer 31

a change of one or more Nitrogen bases in the DNA of an organism

Question 32

genetic variation

Answer 32

this includes a variety of diff genes that may differ from maternal and paternal genes resulting in new genotypes and phenotypes

Question 33

haemophilia

Answer 33

a sex linked disorder characterised by the absence of a blood clotting factor

Question 34

mutation

Answer 34

a sudden change in the sequence/order of nitrogenous bases of a nucleic acid

Question 35

pedigree diagram

Answer 35

a diagram showing the inheritance of genetic disorders over many generation

Question 36

population

Answer 36

a group of organisms of the same species living in the same habitat at the same time

Question 37

stem cells/ meristematic cells

Answer 37

undifferentiated cells that can develop into any cell type