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

B1 - You and Your Genes 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
What is non-coding DNA?
What is non-coding DNA? DNA which does not code for a protein but instead controls gene expression
26
Describe the effect of a gene mutation in | non-coding DNA
Describe the effect of a gene mutation in non-coding DNA Gene expression may be altered, affecting protein production and the resulting phenotype
27
What are gametes?
``` What are gametes? Reproductive cells (e.g. egg and sperm cells) that contain a single copy of each chromosome ```
28
Describe sexual reproduction in terms of | chromosome number
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
Define homozygous
Define homozygous Having two identical alleles of a gene e.g. FF or ff
30
Define heterozygous
Define heterozygous Having two different alleles of a gene e.g. Ff
31
What is a dominant allele?
What is a dominant allele? Describes an allele that is always expressed Represented with a capital letter e.g. F
32
What is a recessive allele?
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
``` 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. ```
check
34
What is the problem with single gene | crosses?
What is the problem with single gene crosses? | Most characteristics are controlled by multiple alleles rather than just one
35
What are sex chromosomes?
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
Why does the inheritance of a Y chromosome mean that an embryo develops into a male?
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
Check CGP for punnet squares
yessir
38
Other than using a punnett square, how else can single gene inheritance be represented?
Other than using a punnett square, how else can single gene inheritance be represented? Using a family tree
39
Outline how the work of Mendel helped scientists to develop their understanding of genetics
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
What is genome sequencing?
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
Why is genome sequencing important?
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
Outline how genetic testing can be used | to improve healthcare (3)
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
Outline the drawbacks of using genetic | testing in healthcare (2)
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
Outline how genetic testing can be used | in family planning (3)
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
Outline the drawbacks of using genetic | testing in family planning (4)
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
What is genetic engineering?
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
Describe the process of genetic | engineering
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
Describe the benefits of genetic | engineering (3)
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
Describe the risks of genetic engineering
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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