Variation and Inheritance Flashcards Preview

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Flashcards in Variation and Inheritance Deck (18)
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1
Q

What does the DNA molecule consist of

A

Two strands, coiled to form a double helix

2
Q

What is the chemical code in DNA made up of

A

Four bases which hold the two strands of the molecule together

3
Q

How many matching pairs of chromosomes do human have in cells

A

23 pairs

46 in total

4
Q

What cells in the body have 23 individual chromosomes

A

The gametes

Fuse to produce zygote with full number of chromosomes
This process increases variation in a species, genetic information from parents mixes to create new unique individual

5
Q

What happens regarding genes in asexual reproduction

A

All genes come from one parent

Offspring are genetically identical, clones

6
Q

Genetic variation between individuals can be caused by

A

Mutations which alter the genes
Genes and chromosomes shuffled gametes
Random fusion of egg with one out of millions of sperm at fertilisation

7
Q

What are the genes which code for characteristics called

A

Alleles (occur in pairs)

These are alternative forms of a gene

8
Q

In sex chromosomes what determines a male and female using X and Y

A

Female XX

Male XY

9
Q

What is a dominant allele

A

Inherited characteristic even if it is present on only one chromosome in a pair

10
Q

What is a recessive allele

A

Both pairs of chromosomes have to have recessive allele for it to be inherited

11
Q

What is it called if chromosomes in a pair contain different alleles of a gene

A

The individual is heterozygous for that gene or condition

12
Q

What is the genotype

A

A characteristic you can’t necessarily see (in the mirror)

13
Q

What is the phenotype

A

A characteristic you can see (in the mirror)

14
Q

What is it called when a characteristic is determined by just one pair of alleles

A

Monohybrid inheritance

15
Q

What are some inherited diseases

A

Red-green colour blindness:cells in eye cannot distinguish btween red and green light
Sickle cell anaemia: red blood cells become misshaped leading to circulatory problems and oxygen deficiency
Cystic fibrosis: cell membranes produce excess mucus that blocks airways and causes problems with digestion

16
Q

What is a chromosome

Where is it found

A

A single piece of coiled DNA

Found inside the nucleus

17
Q

What can the different causes of variation between same species be described as

A

Genetic or environmental

Often its a combination of both

18
Q

What do DNA molecules control

A

DNA molecules form complete set of instructions on how organism should be constructed and how individual cells should work