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B8- DNA, GENES AND PROTEIN SYNTHESIS > 8.2- DNA AND CHROMOSOMES > Flashcards

8.2- DNA AND CHROMOSOMES Flashcards

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Biology 101 flashcards
1
Q

What are the two types of cells?

A

prokaryotic cells

eukaryotic cells

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2
Q

What are the DNA molecules of prokaryotic cells i.e. bacteria like? (3)

A

shorter
form circle
not associated with protein molecules

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3
Q

Do prokaryotic cells have chromosomes?

A

no

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4
Q

What are the DNA molecules of eukaryotic cells like? (3)

A 
longer 
form line (linear)
occur in association with proteins called histones to form structures called chromosomes
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5
Q

What in eukaryotic cells also contain DNA? (2)

A

mitochondria

chloroplasts

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6
Q

What is the DNA of the mitochondria + chloroplasts in eukaryotic cells like? (3)

A

short
circular
not associated with proteins

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7
Q

When are chromosomes only visible as distinct structures?

A

when cell dividing

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8
Q

How are the chromosomes for the time that the cell is not dividing?

A

widely dispersed throughout nucleus

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9
Q

How do the chromosomes appear when they first become visible at the start of cell division?

A

chromosomes appear as two threads, joined at single point

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10
Q

What is each thread called? (chromosomes appear as two threads, joined at single point)

A

chromatid

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11
Q

Why is each thread called a chromatid?

A

as DNA has already replicated to give two identical DNA molecules

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12
Q

What is the DNA in chromosomes held by?

A

histones

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13
Q

What is done to the considerable length of DNA found in each cell?

A

highly coiled + folded

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14
Q

What sort of helix is DNA?

A

double helix

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15
Q

What is done the DNA helix to fix it in position?

A

helix wound around histones to fix it in position

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16
Q

What happens to the DNA-histone complex?

A

it’s then coiled

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17
Q

What happens after the DNA-histone complex is coiled?

A

looped + further coiled before being packed into chromosome

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18
Q

What can happen as the DNA-histone complex is coiled + looped + further coiled before being packed into chromosome?

A

a lot of DNA is condensed into a single chromosome

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19
Q

How many DNA molecules does does a chromosome contain?

A

a single molecule of DNA

20
Q

What does a single molecule of DNA have along its length?

A

many genes

21
Q

What does each gene occupy?

A

specific position (locus) along DNA molecule

22
Q

In most species, what sort of number of chromosomes are in the cell of adults?

A

even number of chromosomes

23
Q

What are sexually produced organisms the result of?

A

fusion of sperm + egg, each of which contributes one complete set of chromosomes to offspring

24
Q

What is one of each pair of chromosome derived from in sexually produced organisms?

A

one of each pair derived from chromosomes provided by mother in egg (maternal chromosome) + other derived from chromosomes provided by father in sperm (paternal chromosomes)

25
Q

What are the pair of chromosomes known as?

A

homologous pairs

26
Q

What is the total number of chromosomes referred to as?

A

diploid number

27
Q

What is the diploid number in humans?

A

46

28
Q

What is a homologous pair always?

A

always two chromosomes that carry same genes but not necessarily same alleles of genes

29
Q

What happens to chromosomes number in meiosis?

A

halving of number of chromosomes

30
Q

What is the way that meiosis done ensure?

A

each daughter cell receives one chromosomes from each homologous pair

31
Q

What does it mean as each daughter cell receives one chromosomes from each homologous pair from meiosis?

A

each cell receives one gene from each characteristic of organism

32
Q

What happens when the haploid cells combine?

A

diploid state, with paired homologous chromosomes restored

33
Q

What is an allele?

A

one of number of alternative forms of gene

34
Q

How many different forms does each gene exist in?

A

two, occasionally more

35
Q

What is the different forms a gene exists in called?

A

gene

36
Q

Where does each individual inherit one allele from?

A

each of its parents

37
Q

Can the alleles inherited from the parents be the same or different?

A

may be same or different

38
Q

What is each allele like if an individual inherits different alleles?

A

each allele has different base sequence , so different amino acid sequence, so produces different polypeptide

39
Q

What is a mutation?

A

change in base sequence of gene producing new allele of that gene

40
Q

What does a mutation result in (hint- amino acids)

A

different sequence of amino acids being coded for

41
Q

From a mutation, what will the different sequence of amino acids being coded for lead to?

A

production of different polypeptide + hence different protein

42
Q

What happens sometimes with the different protein produced from a mutation?

A

different protein may not function properly or may not function at all

43
Q

When the different protein produced from a mutation is an enzyme, what can happen?

A

may have different shape

44
Q

If the different protein produced from a mutation is an enzyme and it has a different shape, what may happen?

A

new shape may not fit enzyme’s substrate

45
Q

What happens if the new shape may not fit enzyme’s substrate due to mutation?

A

enzyme may not function + this can have serious consequences on organism

B8- DNA, GENES AND PROTEIN SYNTHESIS (5 decks)

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