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Year 13 Inheritance > Inheritance > Flashcards

Flashcards in Inheritance Deck (41)
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1

What is a genotype?

Genetic make up of an organism.
ALL the alleles that an organism has.

2

What is an allele?

Different versions of a gene found at the same locus on a chromosome.

3

What is a gene?

Short section of DNA that codes for a single polypeptide

4

What is a phenotype?

Observable or biochemical characteristics of an organism.
Expression of the genotype and its interaction with the environment.

5

What is a homologous chromosomes

A pair of chromosomes matched in shape and size, which contain the same genes.
Formed when haploid gametes fuse to make zygote at fertilisation

6

Locus

Position of a gene on a chromosome

7

Homozygous

Two alleles at a gene locus are the same

8

Heterozygous

Two alleles at a gene locus are different

9

Dominant allele

The allele of the heterozygote that is expressed in the phenotype

10

Recessive allele

The allele that is only expressed when homozygous. It is not expressed when a dominant allele is present.

11

A dominant allele is ...

Where both alleles are expressed in the phenotype

12

What are multiple alleles?

There are more than two alleles for a particular gene

13

In a diploid human cell how many chromosome pairs are there?

23

14

In meiosis, what happens to the diploid number?

It becomes haploid.
It halves

15

Characteristics are determined by your allele combinations. How many alleles for each characteristic are present in a gamete?

1

16

Pure breeding plants are said to be ...

Homozygous

17

What is the difference between monohybrid inheritance and dihybrid inheritance?

Monohybrid - inheritance of a SINGLE gene
Dihybrid - inheritance of TWO genes (that are located on different chromosomes)

18

Give an example of a characteristic that involves multiple allelles

Blood groups

19

Identify the chromosomes that determine sex

X and Y
In most organisms XX = female and XY = male

20

When might you use a Chi squared test?

Sample size is large (20+)
Data falls int categories
Compare experimental observations with theoretical/expected ones.

21

When performing a statistical test what must you always state before you carry out the test?

Null hypothesis
There is no significant difference between .... and ...

22

What are autosomes?

The chromosomes that are not the sex chromosomes. In humans there are 22 pairs of autosomes.

23

What is meant by autosomal linkage?

Two (or more) genes are carried on the SAME chromosome

24

For autosomal linkage what do we have to assume?

There is no crossing over
Genes remain together during meiosis

25

What is epistasis?

The allele of one gene affects or masks the expression of another allele in the phenotype

26

What phenotypic ratio would you expect for a monohydrid cross between two heterozygous individuals?

3:1
3 dominant : 1 recessive

27

What phenotypic ratio would you expect for a dihybrid cross between two heterozygous individuals?

9:3:3:1

28

A carrier is ....

A person in possession of an allele that is not expressed in the phenotype

29

What phenotypic ratio would you expect for codominant cross between 2 heterozygotes?

1:2:1

30

Sometimes you do not get expected phenotypic ratios because ...

Small sample size
Autosomal linkage
Epistasis