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Biology > B1: You and your genes > Flashcards

B1: You and your genes Flashcards

1
Q

What are the two types of cells?

A

Eukaryotic (animals and plants) and prokaryotic.

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2
Q

What is the difference between a eukaryotic and prokaryotic cell?

A

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

Using a light microscope.

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4
Q

How is genetic information stored in a eukaryotic cell?

A

Within the nucleus, arranged in chromosomes.

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5
Q

How is genetic information stored in a prokaryotic cell?

A

Found free within the cytoplasm as:
* Single large loop of circular DNA
* Plasmids.

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6
Q

What are plasmids?

A
  • 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

The entire genetic material of an organism.

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8
Q

What is a chromosome?

A

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

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

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10
Q

Define gene.

A

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

Different versions of the same gene.

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12
Q

Define genotype.

A

An organism’s genetic composition, describes all alleles.

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13
Q

Define phenotype.

A

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

Nucleotides.

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15
Q

What are DNA nucleotides made up of?

A
  • 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
  • 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
  • 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
  • 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

The formation of a protein from a gene.

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20
Q

Outline protein synthesis.

A
  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.
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21
Q

Why does mRNA rather than DNA join to a ribosome in the cytoplasm?

A

DNA is too large to leave the nucleus so cannot reach the ribosome.

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22
Q

What is a mutation?

A

A random change to the base sequence of DNA which results in genetic variants.

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23
Q

State the three types of gene mutation.

A
  • Insertion
  • Deletion
  • Substitution.
24
Q

Describe the effect of a gene mutation in coding DNA.

A
  • 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

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

Gene expression may be altered, affecting protein production and the resulting phenotype.

27
Q

What are gametes?

A

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

Two gametes with a single copy of each chromosome fuse, resulting in an embryo with two chromosomes for each gene and two copies of each allele

29
Q

Define homozygous

A

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

30
Q

Define heterozygous

A

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

31
Q

What is a dominant allele?

A

Describes an allele that is always expressed; represented with a capital letter e.g. F

32
Q

What is a recessive allele?

A

An allele that is only expressed in the absence of a dominant allele; represented with a small letter e.g. f

33
Q

Using a punnett square, what is the offspring proportion from a homozygous recessive female (ff) and a heterozygous male (Ff)?

A

50% chance of Ff (carrier), 50% chance of ff (homozygous recessive)

34
Q

What is the problem with single gene crosses?

A

Most characteristics are controlled by multiple alleles rather than just one

35
Q

What are sex chromosomes?

A

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

Testes development in an embryo is stimulated by a gene present on the Y chromosome

37
Q

Using a punnett square, what is the probability of having offspring that is female?

A

50% chance of female (XX)

38
Q

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

A

Using a family tree

39
Q

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

A
  • Studied the inheritance of different phenotypes of pea plants
  • Established a correlation between parent and offspring phenotypes
  • Noted that inheritance was determined by ‘units’ passed on to descendants
  • Devised the terms ‘dominant’ and ‘recessive’
40
Q

What is genome sequencing?

A

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
  • 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

Fill in the blank: A female who is homozygous recessive for cystic fibrosis has the genotype _______.

A

ff

43
Q

Fill in the blank: A heterozygous male for cystic fibrosis has the genotype _______.

A

Ff

44
Q

True or False: A recessive allele is expressed when a dominant allele is present.

A

False

45
Q

True or False: Mendel’s work established the concepts of dominant and recessive traits.

A

True

46
Q

How can genetic testing improve healthcare?

A

Enables awareness of potential risks, early treatment plans, and prediction of a patient’s reaction to certain drugs

Key aspects include lifestyle changes to reduce risks and personalized medicine.

47
Q

What are the drawbacks of using genetic testing in healthcare?

A

Discrimination by employers, insurance firms, and potential for anxiety or depression

These drawbacks highlight ethical concerns regarding genetic information.

48
Q

How can genetic testing be used in family planning?

A

Parental carrier testing, prenatal testing, and fetal testing via amniocentesis or chorionic villus sampling

These methods help identify genetic disorders before birth.

49
Q

What are the drawbacks of using genetic testing in family planning?

A

False-positive/false-negatives, ethical considerations, risk of miscarriage, and potential for ‘designer babies’

Ethical concerns arise from embryo destruction and selective termination.

50
Q

What is genetic engineering?

A

The changing of the genome of an organism by the insertion of a desired gene from another organism

This process enables the formation of organisms with beneficial characteristics.

51
Q

Describe the process of genetic engineering.

A
  1. Desired gene isolated using enzymes
  2. Gene replicated
  3. Gene placed into vector
  4. Vector mixed with target cells
  5. Modified cells identified and cultured

Vectors can include plasmids or viruses.

52
Q

What are the benefits of genetic engineering?

A
  1. Increased crop yields
  2. Useful in medicine
  3. Production of scarce resources

Examples include herbicide-resistance crops and insulin-producing bacteria.

53
Q

What are the risks of genetic engineering?

A
  1. Unknown long-term effects of GM crops
  2. Negative environmental impacts
  3. Late-onset health problems in GM animals

Risks include biodiversity reduction and contamination of non-GM crops.

54
Q

Fill in the blank: Genetic testing enables awareness of potential risks and the introduction of _______ to reduce these associated risks.

A

lifestyle changes

55
Q

True or False: Genetic testing can lead to discrimination by employers if a person is likely to develop a disease.

A

True

56
Q

Fill in the blank: The process of genetic engineering begins with the desired gene being _______ using enzymes.

A

isolated

57
Q

What is one ethical consideration associated with genetic testing in family planning?

A

Destruction of embryos

This raises moral questions about the value of potential life.

Biology (4 decks)

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