inheritance

Question 1

allele

Answer 1

different version of the same gene

Question 2

genes

Answer 2

the information that is passed from parent to offspring that influences the structure,
physiology or behaviour of an organism
Genes are a sections of coding DNA that code for a specific protein in the body
Genes are given a name consisting of a group of up to 5 characters

Question 3

genotype

Answer 3

the combination of alleles that code for a trait​
In humans, we have 2 alleles for each gene - one allele from each parent ​
alleles are assigned a capital or lowercase letter to signify whether they are dominant or recessive ​

Question 4

dominant alleles

Answer 4

the version of the gene that overpowers the recessive gene​
Only one copy of a dominant allele is required for it to be expressed​

Question 5

recessive alleles

Answer 5

-versions of a gene that can skip generations and are overpowered by the dominant allele​
-You need 2 copies of a recessive allele to show the trait it encodes. This means BOTH parents need to pass on the recessive gene.​

Question 6

homozygous

Answer 6

the alleles an organism has for a particular gene are identical​
This can be either homozygous dominant (AA) or homozygous recessive (aa)​

Question 7

heterozygous

Answer 7

means that the alleles an organism has for a particular gene are different​
This means the organism contains one dominant and one recessive allele (Aa)​

Question 8

phenotype

Answer 8

the expression (physical appearance) of a particular genotype​

Question 9

complete dominance

Answer 9

the dominant allele completely masks the recessive allele​, complete dominance includes, homozygous dominant, homozygous recessive and heterozygous (AA,Aa,aa)

Question 10

incomplete dominance

Answer 10

he traits blend in the heterozygote – creating a third phenotype ​e.g. Red + white = pink, alleles are represented by both capital letter e.g. PW

Question 11

co dominance

Answer 11

he traits blend in the heterozygote – creating a third phenotype , alleles are represented by capital letters

Question 12

di hybrid crosses

Answer 12

A dihybrid cross is a cross in which alleles of two different genes are involved.​

The individuals in this type of cross can be either homozygous or heterozygous for each trait.​

Four kinds of gametes are produced by each parent

Question 13

pedigree chart

Answer 13

A record of a family and their genetic conditions​
It is used to determine if a condition is dominant/recessive/x-linked​

Question 14

autosomal

Answer 14

Autosomal traits are carried on the autosomes (chromosomes 1-22) and can be dominant or recessive​

Question 15

sex linked

Answer 15

​Sex-linked traits are carried on the X or Y chromosome and can also be dominant or recessive

Question 16

sex linked traits

Answer 16

Males: XY – only inherit one copy of the X chromosome (from their mother)​

Females: XX – inherit one copy of the X chromosome from their mother and one copy from their father​

X-linked recessive traits – males who have the recessive allele on their X chromosome will ALWAYS express the recessive phenotype as they only have one X chromosome​

X-linked dominant traits – females are affected more as they have two chances at inheriting the dominant allele​

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Question 17

x- linked traits (haemophilia)

Answer 17

X-linked traits require a special notation​
Haemophilia is an X-linked recessive trait –The alleles are written as follows:​
Dominant: XH​
Recessive: Xh​

​A male without hemophilia has the genotype: XHY​
A male with hemophilia has the genotype: XhY​
A female without haemophilia: XHXH or XHXh​
A female with haemophilia: XhXh​

Question 18

X linked recessive

Answer 18

100% incidence of affected sons from and affected mother suggests x linked recessive

Question 19

x linked dominant

Answer 19

100% incidence of affected daughters from an affected father suggests x linked dominance

Question 20

y linked

Answer 20

only males are affected

Question 21

autosomal dominant

Question 22

autosomal reccesive

Question 23

epigenetics

Answer 23

genes can be turned on or off depending on signals from the environment.

Question 24

DNA methylation

Answer 24

prevents certain genes from being expressed.​ can be caused by , temperature, nutrient availability and radiation

Question 25

polygenetics

Answer 25

A polygenic trait is a characteristic, such as height or skin color, that is influenced by two or more genes.