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Science 2023 > Genetics Test Revision (27th feb) > Flashcards

Genetics Test Revision (27th feb) Flashcards

(70 cards)

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1
Q

what does dna stand for?

A

deoxyribonucleic acid

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2
Q

who first described the structure of dna and when?

A

james watson and francis crick, 1953

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3
Q

what is the shape of dna?

A

twisted double helix

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4
Q

does the structure of dna change in all organisms?

A

no, it stays the same in every organism

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5
Q

what is dna made up of?

A

smaller molecules called nucleotides

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6
Q

what is a nucleotide made up of?

A

a phosphate group, a deoxyribose suger, and one of 4 nitrogen-rich bases

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7
Q

what are the 4 nitrogen-rich bases?

A

adenine, thymine, cytosine, guanine

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8
Q

which bases pair together?

A

adenine pairs with thymine, guanine pairs with cytosine

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9
Q

what is the base pairing known as?

A

complementary base pairing

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10
Q

what are chromosomes?

A

long, thread-like structures found in the nuclei of all cells in the human body that contain a nucleus (made up of coiled up dna)

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11
Q

what are chromosomes wrapped around?

A

proteins

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12
Q

how many chromosomes do most human cells have?

A

46

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13
Q

how much dna do most human cells have?

A

2 metres

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14
Q

how many bases do most human cells have?

A

6 billion

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15
Q

how many genes do most human cells have?

A

20,000

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16
Q

which are the only cells that dont have 46 chromosomes, and how many chromosomes do they have?

A

gametes, with 23 chromosomes each

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17
Q

what are gametes?

A

sperm and egg cells

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18
Q

how is the gender/sex of a baby determined?

A

by the sperm

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19
Q

how many sex chromosomes are in each cell?

A

2

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20
Q

what are the 2 sex chromosomes?

A

x and y chromosomes

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21
Q

which 2 sex chromosomes does a female have?

A

xx

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22
Q

which 2 sex chromosomes does a male have?

A

xy

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23
Q

what are the other 44 chromosomes (not including sex chromosomes) called?

A

autosomes

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24
Q

how many pairs are autosomes grouped into?

A

22

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25
what does a chromosome pair have to be?
homologous (the same)
26
what are the features of a homologous pair?
1. they're the same length 2. they have a structure called the centromere in the same spot (the point where the 2 chromatids join together) 3. they have genes for particular characteristics at the same points along their lengths
27
what is a karyotype?
an organism's complete set of chromosomes
28
how is a karyotype ordered?
shortest to longest
29
what is a gene?
a section of dna arranged along a chromosome
30
how many genes are on ecach chromosome?
200-2000
31
what differs between genes?
1. the order of the bases along the dna strand 2. the number of bases in that section of dna
32
what do genes do?
each gene codes for a specific protein
33
what do proteins do?
create the structures for and perform actions needed for cells to survive, grow, and function
34
what are the 3 types of proteins?
structural, enxymes, regulatory
35
examples of structural proteins?
collagen (found in tendons and ligaments) keratin (found in skin, hair, nails, scales, and feathers)
36
examples of enzymes?
amylase (helps digest starch) lactase (helps digest lactose which is the sugar found in milk) lipase (helps digest fats)
37
examples of regulatory proteins?
growth hormone (stimulates growth and cell reproduction) insulin (controls blood glucose levels)
38
what do egg and sperm cells form when they join together?
a zygote
39
how many chromosomes does a zygote have?
46
40
how does a zygote replicate?
mitosis
41
why does your body continue to replicate cells even after you're fully developed?
to replace damaged or dead cells
42
what is mitosis?
a process of cell division where 2 identical daughter cells are produced from the parent cell
43
what are the steps of mitosis?
1. the parent cell replicates its dna 2. the dna condenses into chromosomes 3. the chromosomes align at the equator (the middle) of the cell) 4. sister chromatids are pulled apart to the poles of the cell 5. the cell membrane pinches off, creating 2 daughter cells
44
why does the parent cell replicate its dna first?
because each daughter cell needs a full copy of the dna found in the parent cell
45
why are chromosomes x shaped?
because the 2 copies of the dna made during the replication are still attached at the centromere
46
how are chromosomes counted?
by their number of centromeres
47
how do the chromosomes align in the middle of the cell?
the nuclear membrane breaks down around them
48
what happens after the chromatids are at the poles of the cell?
new nuclei form around the chromosomes at each end
49
what makes up 90% of the cell cycle?
interphase (when cells arereplicating their dna)
50
what is translation?
when the information in the dna is used to produc a protein
51
where a chromosomes located and do they ever leave?
chromosomes never leave the nucleus
52
what is it called when a copy of dna is made?
transcription
53
where does the copied dna move to?
the ribosomes
54
what occurs in the ribosomes?
proteins are created (translation)
55
what are amino acids?
the building blocks of proteins
56
what is a triplet of dna called?
a codon
57
when does a chain of amino acids stop growing?
when a stop codon ends it
58
what are genetic mutations?
changes to your dna sequence that happen during cell division when your cells make copies of themselves
59
are genetic mutations good or bad?
they can be bad (cancer) or they can be good (helpful adaptations)
60
what are some symptoms of genetic mutations?
- physical characteristics (facial abnormalities, etc.) - problems with cognitive function + developmental delays - vision or hearing loss - breathing problems - increased rick of developing cancer
61
when do genetic mutations occur?
during cell division
62
what are the 5 types of mutations?
silent, missense, nonsense, frameshift, point
63
what is a silent mutation?
when a single base on the dna strand changes, however, it still codes for the same protein
64
what is a missense mutation?
when more than one base is changed, causing the gene to produce a different protein, which may not function properly and cause disease
65
what is a nonsense mutation?
when a mutation causes the cells to stop reading the information on the gene before it's end (incomplete protein created, cannot function)
66
what is a frameshift mutation?
caused by the insertion or deletion of one or more bases (all the information following the mutation is jumbled and cannot be 'read' to create a protein)
67
what is a point mutation?
when only one base is changed however, a different protein is coded
68
what is a mutagen?
an agent that causes mutations
69
what are the main groups mutagens fall into?
radiation, chemical, biologial
70
what is a carcinogen?
a mutagen that causes a mutation that leads to cancer

Science 2023 (2 decks)

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