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Edexcel GCSE Combined Science Biology > Genetics > Flashcards

Flashcards in Genetics Deck (51)
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1
Q

What are DNA strands called?

A

Polymers

2
Q

Name the 4 bases for a DNA unit?

A

Adenine
Thymine
Cytosine
Guanine

3
Q

What shape describes DNA?

A

Double helix

4
Q

Complementary bases

What is matched with A Adenine?

A

T

Thymine

5
Q

Complementary bases

What goes with C Cytosine?

A

G

Guanine

6
Q

What are complementary bases joined together with?

A

Weak hydrogen bonds

7
Q

How is your DNA passed onto the next generation?

A

Reproduction

8
Q

What are chromosomes?

A

Long, coiled up molecules of DNA

9
Q

Where are chromosomes found?

A

Nucleus of eukaryotic cells

10
Q

What determines what protein is produced?

A

The sequence of bases in the gene

11
Q

What practical test can you use to extract DNA from fruit cells?

A

Add detergent and salt
Detergent breaks down cell membranes to release DNA
Salt makes DNA stick together

12
Q

Who won Nobel prize for their work on DNA?

A

Crick Watson Wilkins

13
Q

Why is it useful to use salt when extracting DNA from fruit cells?

A

Salt makes DNA stick together

14
Q

How many chromosomes do human cells contain?

A

46

15
Q

How many chromosomes in a haploid cell?

A

23

16
Q

In flowering plants where are male gametes found?

A

Pollen

17
Q

Where are female gametes found in flowering cells?

A

Ovaries at bottom of stigma

18
Q

What are normal cells with full number of chromosomes called?

A

Diploid

19
Q

What are reproductive cells called?

A

Gametes

20
Q

What are animal gametes better known as ?

A

Sperm and egg cells

21
Q

What is a zygote?

A

A fertilised egg

22
Q

What happens when a male gametes fuses with a female gamete?

A

Produces a fertilised egg

23
Q

What happens when a zygote undergoes cell division by mitosis?

A

Develops into an embryo

24
Q

What is the difference between meiosis and mitosis?

A

Doesn’t produce identical cells

25
Q

Does meiosis happen in other organs?

A

No just reproductive organs

26
Q

How many divisions in meiosis?

A

2

27
Q

How is genetic variation created?

A

Mixture of mother’s and father’s genes

28
Q

What is a gene?

A

A stretch of DNA that determines a certain trait

29
Q

What is an allele?

A

A form of a gene
Eg. Gene for eye colour has several variations
One for blue eyes, one for brown eyes etc.

30
Q

How many versions or alleles of genes do you have?

A

2

One on each chromosome

31
Q

What is homozygous?

A

If 2 alleles are the same

32
Q

What is heterozygous?

A

If 2 alleles are different

33
Q

Dominant alleles have a capital or small letter?

A

Capital

34
Q

Do dominant alleles overrule recessive alleles?

A

Yes

35
Q

How can organisms display recessive characteristics?

A

Both alleles must be recessive

36
Q

What is genotype?

A

Part of genetic make up of a cell which determines a characteristic or phenotype

37
Q

What is a phenotype?

A

A characteristic

Eg eye colour

38
Q

Which sex have an X and a Y chromosome?

A

Males

39
Q

What letter combination do female chromosomes have?

A

XX

40
Q

What maths term is used to determine sex of babies?

A

Probability

41
Q

What is genetic variation within a species ?

A

All dogs are same species

Pug looks different to Dalmatian

42
Q

What is a genetic mutation?

A

Changes to base sequence of DNA

43
Q

What is human genome project?

A

Research to map over 20,000 genes

44
Q

How could information from human genome project be used to help prevent individuals from developing certain diseases?

A

Design new drugs
If doctors know what genes predispose people to diseases individually treated
Identify faulty alleles

45
Q

Who came up with theory of natural selection and evolution ?

A

Charles Darwin

46
Q

What system classifies organisms?

A

Five kingdom classification system

47
Q

What are 5 kingdoms?

A
Animals
Plants
Fungi
Prokaryotes 
Protists
48
Q

Name sub divisions of kingdoms?

A
Phylum
Class
Order
Family
Genus
Species
49
Q

What is selective breeding?

A

Take best plants or animals to breed to get best offspring

50
Q

Name some attractive features for selective breeding?

A

Animals that produce more milk or meat
Crops with disease resistance
Dogs with a gentle temperament
Plants that produce bigger fruit

51
Q

Give 3 problems selective breeding can cause

A

In breeding and reduces gene pool
Causes health problems or harmful genetic defects
If new disease appears, not much variation so less chance of resistance alleles