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Biology Flashcards - OCR 21st Century > B1 - You and Your Genes > Flashcards

B1 - You and Your Genes Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

State the two types of cell

A

State the two types of cell
Eukaryotic (animals and plants) and
prokaryotic

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2
Q

What is the difference between a

eukaryotic and prokaryotic cell?

A

What is the difference between a eukaryotic and
prokaryotic cell?
A eukaryotic cell contains a nucleus and
membrane-bound organelles. A
prokaryotic cell does not.

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3
Q

How can the structure of eukaryotic cells

be observed?

A

How can the structure of eukaryotic cells be
observed?
Using a light microscope

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4
Q

How is genetic information stored in a

eukaryotic cell?

A

How is genetic information stored in a eukaryotic
cell?
Within the nucleus, arranged in
chromosomes

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5
Q

How is genetic information stored in a

prokaryotic cell?

A 
How is genetic information stored in a prokaryotic 
cell?
Found free within the cytoplasm as:
● Single large loop of circular DNA
● Plasmids
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6
Q

What are plasmids?

A

What are plasmids?
● Small, circular loops of DNA found free in the
cytoplasm and separate from the main DNA
● Carry genes that provide genetic advantages
e.g. antibiotic resistance

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7
Q

Define genome

A

Define genome

The entire genetic material of an organism

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8
Q

What is a chromosome?

A

What is a chromosome?

A long, coiled molecule of DNA that carries genetic information in the form of genes

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9
Q

What is DNA?

A

What is DNA?

A double-stranded polymer of nucleotides, wound to form a double helix

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10
Q

Define gene

A

Define gene

A section of DNA that codes for a specific sequence of amino acids which undergo polymerisation to form a protein

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11
Q

What are alleles?

A

What are alleles?

Different versions of the same gene

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12
Q

Define genotype

A

Define genotype

An organism’s genetic composition, describes all alleles

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13
Q

Define phenotype

A

Define phenotype
An organism’s observable characteristics due to interactions of the genotype and environment (which can modify the phenotype)

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14
Q

What are the monomers of DNA?

A

What are the monomers of DNA?

Nucleotides

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15
Q

What are DNA nucleotides made up of?

A

What are DNA nucleotides made up of?
● Common sugar
● Phosphate group
● One of four bases: A, T, C or G

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16
Q

Describe how nucleotides interact to

form a molecule of DNA

A

Describe how nucleotides interact to form a molecule
of DNA
● Sugar and phosphate molecules join to form a
sugar-phosphate backbone in each DNA strand
● Base connected to each sugar
● Complementary base pairing: A pairs with T, C pairs with G

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17
Q

Explain how a gene codes for a protein

A

Explain how a gene codes for a protein

● A sequence of three bases in a gene forms a triplet
● Each triplet codes for an amino acid
● The order of amino acids determines the structure
and function of protein formed

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18
Q

Describe the differences between mRNA

and DNA

A

Describe the difference between mRNA and DNA

● mRNA is single stranded whereas
DNA is double stranded
● mRNA uses U whereas DNA uses T

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19
Q

What is protein synthesis?

A

What is protein synthesis?

The formation of a protein from a gene

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20
Q

Outline protein synthesis

A

Outline protein synthesis
1. In the nucleus, DNA is used as a template to form mRNA
2. mRNA exits the nucleus, moving into the cytoplasm where
it attaches to a ribosome
3. The ribosome joins amino acids in a specific order,
dictated by mRNA to form a protein.

21
Q

Why does mRNA rather than DNA join to

a ribosome in the cytoplasm

A

Why does mRNA rather than DNA join to a ribosome
in the cytoplasm?
DNA is too large to leave the nucleus so cannot reach the ribosome

22
Q

What is a mutation?

A

What is a mutation?
A random change to the base sequence
of DNA which results in genetic variants

23
Q

State the three types of gene mutation

A

State the three types of gene mutation

● Insertion
● Deletion
● Substitution

24
Q

Describe the effect of a gene mutation in

coding DNA

A

Describe the effect of a gene mutation in coding
DNA

● If a mutation changes the sequence of amino acids,
protein structure and function may change
● If a mutation does not change the sequence of amino acids, there is no effect on protein structure or
function

25
Q

What is non-coding DNA?

A

What is non-coding DNA?
DNA which does not code for a protein
but instead controls gene expression

26
Q

Describe the effect of a gene mutation in

non-coding DNA

A

Describe the effect of a gene mutation in non-coding
DNA
Gene expression may be altered, affecting protein production and the resulting phenotype

27
Q

What are gametes?

A 
What are gametes?
Reproductive cells (e.g. egg and sperm cells) that contain a single copy of each chromosome
28
Q

Describe sexual reproduction in terms of

chromosome number

A

Describe sexual reproduction in terms of
chromosome number
● Two gametes with a single copy of each
chromosome fuse
● Resulting embryo has two chromosomes for
each gene and two copies of each allele

29
Q

Define homozygous

A

Define homozygous
Having two identical alleles of a gene
e.g. FF or ff

30
Q

Define heterozygous

A

Define heterozygous
Having two different alleles of a gene
e.g. Ff

31
Q

What is a dominant allele?

A

What is a dominant allele?
Describes an allele that is always expressed
Represented with a capital letter e.g. F

32
Q

What is a recessive allele?

A

What is a recessive allele?
An allele that is only expressed in the absence of a dominant allele
Represented with a small letter e.g. f

33
Q 
A female who is homozygous recessive 
for cystic fibrosis (ff) has a child with a 
heterozygous male (Ff). Draw a punnett 
square to illustrate this single gene 
inheritance.
A

check

34
Q

What is the problem with single gene

crosses?

A

What is the problem with single gene crosses?

Most characteristics are controlled by multiple alleles rather than just one

35
Q

What are sex chromosomes?

A

What are sex chromosomes?
A pair of chromosomes that determines sex:
● Males have an X and a Y chromosome
● Females have two X chromosomes

36
Q

Why does the inheritance of a Y
chromosome mean that an embryo
develops into a male?

A

Why does the inheritance of a Y chromosome mean
that an embryo develops into a male?
Testes development in an embryo is stimulated by a gene present on the Y chromosome

37
Q

Check CGP for punnet squares

A

yessir

38
Q

Other than using a punnett square, how
else can single gene inheritance be
represented?

A

Other than using a punnett square, how else can
single gene inheritance be represented?
Using a family tree

39
Q

Outline how the work of Mendel helped
scientists to develop their understanding
of genetics

A

Outline how the work of Mendel helped scientists to
develop their understanding of genetics
● Mendel studied the inheritance of different phenotypes of pea plants
● He established a correlation between parent and offspring phenotypes
● He noted that inheritance was determined by ‘units’ passed on to
descendants
● Using gene crosses, he devised the terms ‘dominant’ and ‘recessive’

40
Q

What is genome sequencing?

A

What is genome sequencing?
Finding out the order of nucleotides in the DNA of an organism, enabling the function and interaction of genes to be assessed

41
Q

Why is genome sequencing important?

A

Why is genome sequencing important?

● Allows the comparison of genomes of healthy
individuals with patients who have a disease
● Potential disease-causing alleles are identified
● Individuals can then undergo genetic testing for these alleles

42
Q

Outline how genetic testing can be used

to improve healthcare (3)

A

Outline how genetic testing can be used to improve
healthcare (3)
● Enables awareness of potential risks and the introduction
of lifestyle changes to reduce these associated risks
● Enables early treatment plans to begin
● Prediction of a patient’s reaction to certain drugs -
‘personalised medicine’

43
Q

Outline the drawbacks of using genetic

testing in healthcare (2)

A

Outline the drawbacks of using genetic testing in
healthcare (2)
● Discrimination by employers, insurance firms
etc. if a person is likely to develop a disease
● Person may develop anxiety, depression etc.

44
Q

Outline how genetic testing can be used

in family planning (3)

A

Outline how genetic testing can be used in family
planning (3)
● Parental carrier testing - parents tested for the presence of recessive disease-causing alleles
● Prenatal testing - egg fertilised In vitro, embryo tested for genetic disorders
● Fetus tested for genetic disorders via amniocentesis or chorionic villus sampling (CVS)

45
Q

Outline the drawbacks of using genetic

testing in family planning (4)

A

Outline the drawbacks of using genetic testing in
family planning (4)
● False-positive/false-negatives
● Ethical considerations - involves the destruction of
embryos and potential terminations
● Amniocentesis and CVS carry a slight risk of miscarriage
● Could lead to ‘designer babies’

46
Q

What is genetic engineering?

A

What is genetic engineering?
● The changing of the genome of an organism by the
insertion of a desired gene from another organism
● Enables the formation of an organism with beneficial
characteristics

47
Q

Describe the process of genetic

engineering

A

Describe the process of genetic engineering

  1. Desired gene isolated using enzymes
  2. Gene replicated
  3. Gene placed into vector (e.g. plasmid, virus)
  4. Vector mixed with and ‘taken up’ by target cells
  5. Modified cells identified, selected and cultured
48
Q

Describe the benefits of genetic

engineering (3)

A

Describe the benefits of genetic engineering (3)
● Increased crop yields for growing population e.g.
herbicide-resistance, disease-resistance
● Useful in medicine e.g. insulin-producing bacteria, antithrombin in goat milk
● GM crops produce scarce resources e.g. GM golden rice produces beta-carotene (source of vitamin A in the body)

49
Q

Describe the risks of genetic engineering

A

Describe the risks of genetic engineering (3)
● Long-term effects of consumption of GM crops unknown
● Negative environmental impacts e.g. reduction in
biodiversity, impact on food chain, contamination of
non-GM crops forming ‘superweeds’
● Late-onset health problems in GM animals

Biology Flashcards - OCR 21st Century (11 decks)

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