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Cell Division & Inheritance Flashcards

1
Q

What is the definition of mitosis?

A

Produces 2 daughter cells from 1 parent cell; daughter cells are genetically identical to parent cell.

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2
Q

What is mitosis needed for?

A

Growth & repair; used for asexual reproduction.

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3
Q

What is the definition of meiosis?

A

Division 1 - DNA copied, cell divides, randomly sorts chromosomes. Division 2 - 4 genetically different haploid gametes.

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4
Q

What is meiosis used for?

A

Used to make gametes.

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5
Q

What is the definition of diploid?

A

All chromosomes are in pairs, half from mother and half from father; like human cells.

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6
Q

What is the definition of haploid cells?

A

One copy from each chromosome; like gametes.

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7
Q

How is DNA arranged?

A

Long molecules, called chromosomes.

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8
Q

How many chromosomes do humans have?

A

46 - 23 pairs.

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9
Q

Where are chromosomes stored?

A

Nucleus.

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10
Q

What do chromosomes contain?

A

Genes.

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11
Q

What is the definition of a gene?

A

Sections of DNA that contain instructions to make a particular protein.

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12
Q

What is the definition of a genome?

A

Total DNA content of an individual.

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13
Q

Why do we have 2 copies of every gene?

A

1 paternal chromosome & 1 maternal chromosome.

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14
Q

What is the definition of alleles?

A

Different versions of the same gene.

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15
Q

What is the definition of a genotype?

A

Combination of alleles present for a particular gene.

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16
Q

What is the definition of homozygous?

A

Both alleles are the same.

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17
Q

What is the definition of heterozygous?

A

Both alleles are different.

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18
Q

What is the definition of a phenotype?

A

Characteristic resulting from the genotype.

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19
Q

What is the definition of a dominant allele?

A

Shows characteristic if genotype is homozygous or heterozygous for that allele (represented by capital letters).

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20
Q

What is the definition of a recessive allele?

A

Only shows characteristics if genotype is homozygous for that allele (represented by lowercase letters).

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21
Q

How is inheritance of sex determined?

A

By inheritance of sex chromosomes (XY=male, XX=female).

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22
Q

What are pedigrees for?

A

Used to identify inheritance patterns in families; can determine if an inherited disorder is dominant or recessive.

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23
Q

What is a monogenic characteristic?

A

Result from different alleles of a single gene; characteristics are categoric (e.g. blood group).

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24
Q

What is a polygenic characteristic?

A

Result from inheritance of different alleles in multiple genes; characteristics are continuous.

25
What does DNA stand for?
Deoxyribonucleic acid.
26
What does RNA stand for?
Ribonucleic acid.
27
What is DNA?
2 strands forming double helix; each strand has a sugar-phosphate backbone & a series of nitrogenous bases. 4 bases: A(adenine) pairs with T(thymine), G(guanine) pairs with C(cytosine).
28
What is RNA?
Single stranded; long strand with sugar phosphate backbone; uses ribose instead of deoxyribose. 4 bases: A(adenine) pairs with T(thymine), C(cytosine) pairs with U(uracil).
29
What do codominant alleles produce?
A combination of phenotypes of each allele in heterozygotes.
30
How does protein synthesis happen?
DNA - (transcription, in nucleus) - mRNA - (translation, on ribosomes in cytoplasm) - protein.
31
What are the similarities between RNA & DNA?
Both are long molecules with sugar phosphate backbones; both have bases A, G, C.
32
What are the differences between RNA & DNA?
RNA has U instead of T; RNA is a single strand, DNA has 2 strands; RNA has ribose as a sugar, DNA has deoxyribose.
33
What is transcription?
DNA is used as a template to produce a molecule of messenger RNA (mRNA).
34
How does transcription work?
DNA helix is locally unwound, exposing bases on template strand. RNA nucleotides (monomers) pair with bases on the template strands of DNA, joined together by RNA polymerase. The mRNA molecule detaches from the template strand & the DNA reforms.
35
What is translation?
Genetic code - mRNA is read in chunks of 3 bases codons; different codons represent different amino acids.
36
How does translation work?
mRNA binds to the ribosomes in the cytoplasm; a tRNA bringing a specific amino acid comes to the ribosome (the anticodon on the tRNA pairs with the anticodon on the mRNA); the growing protein is added to the next amino acid; the mRNA is moved along the ribosome and the empty tRNA leaves.
37
What does the sequence of amino acids in a protein determine?
How it folds & carries out its function.
38
What is a mutation?
Change in a DNA sequence.
39
What are the effects of a mutation?
Change in base sequence of a gene can change amino acids in a protein, changing how it folds or functions.
40
Why do most mutations not affect the characteristic?
Silent mutations: some amino acids have multiple codons so mutation doesn't change amino acid; 99% of genome doesn't encode proteins, so mutation may not have an effect; changing amino acid doesn't affect the structure of a protein (e.g. mutation not in active site).
41
What is variation caused by?
Genetic factors, environmental factors or both.
42
What are examples of genetic variation?
Eye colour, natural hair colour, skin colour, height, predisposition to genetic disease.
43
What are examples of environmental variation?
Dyed/sun bleached hair, weight.
44
What are examples of genetic variation and environmental variation?
Skin colour, disease risk.
45
What is the process of natural selection?
Variation caused by mutation; selection pressure; survival of the fittest; reproduction.
46
What is variation caused by mutation in natural selection?
Some mutations lead to generation of new alleles causing variation in phenotypes.
47
What is selection pressure in natural selection?
An external event that puts pressure on survival of a population, e.g. change in temp, predators, disease, competition.
48
What is survival of the fittest in natural selection?
Individuals in a species with alleles that help to adapt to selection pressure are more likely to survive.
49
What is reproduction in natural selection?
Surviving individuals reproduce & pass favourable alleles on to the next generation.
50
What is the process of evolution?
Reproductive isolation; natural selection; speciation.
51
What is reproductive isolation in evolution?
A population is split so different populations are unable to reproduce with each other.
52
What is natural selection in evolution?
Different populations are subjected to different selection pressures.
53
What is speciation in evolution?
Eventually the different populations differ so much they become different species.
54
What are antibiotics?
Medicines that kill bacteria & are used to treat bacterial infections.
55
What is variation caused by mutation of antibiotics?
Mutations slightly increase resistance to an antibiotic.
56
What is the selection pressure of antibiotics?
Presence of antibiotic.
57
What is survival of the fittest of antibiotics?
Those more resistant are more likely to survive.
58
What is reproduction of antibiotics?
Increased resistance passed onto future generations.
59
What are human impacts leading to antibiotic resistance?
Not finishing courses of antibiotics - not all infection removed; misuse of antibiotics - healthcare (prescribing inappropriately e.g. for viral infections), agriculture (routine use in animal feed); antibiotic rich environments (e.g. hospitals).

Biology (30 decks)

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