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Biology - BW > Genetics And Cell Division > Flashcards

Genetics And Cell Division Flashcards

1
Q

What shape is DNA

A

Double helix

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2
Q

What small molecules are DNA made of

A

Nucleotides

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3
Q

How many bases does DNA have

A

4

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4
Q

What are the 4 bases for DNA

A

A - adenine
c- cytosine
G- guanine
T- thymine

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5
Q

Each base on a nucleotide forms what bonds to the complimentary base pairing on the other Strand?

A

Hydrogen bonds

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6
Q

What are the complimentary base pairing

A

Adenine - thymine
Cytosine - guanine

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7
Q

What does DNA control the production of

A

Proteins (protein synthesis) in cells

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8
Q

What is a gene

A

A section of DNA that codes for a particular
Protein

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9
Q

What are proteins made up of

A

Chains of amino acids
Each protein has its own particular number and order of amino acids

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10
Q

What decides the order of amino acids in a protein

A

The order of the bases in a gene

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11
Q

why can’t DNA molecules move out of the nucleus

A

Becasue they’re are very large

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12
Q

Where does protein synthesis happen

A

In the cytoplasm at organelles called ribosomes

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13
Q

As DNA can’t leave the nucleus amd protein synthesis happen in the cytoplasm on ribosomes what happens

A

A copy of the gene that codes for it is made in the nucleaus. This copy is smaller than the DNA so it can move into the cytoplasm where it can be used to make the protein

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14
Q

In protein synthesis the copy of the gene is made from a molecule called ?

A

Messenger RNA (mRNA)

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15
Q

DNA is used as a —— to make - - - molecule

A

Template
mRNA

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16
Q

what is RNA made up of

A

Nucleotides
Which each have a base

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17
Q

The bases on the RNA nucleotides line up next to their complementary bases on what?

A

The DNA template

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18
Q

What base is not on RNA

A

Thymine (T)

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19
Q

As there is no thymine in RNA what binds to any adenine in DNA instead

A

Uracil (U)

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20
Q

Once the bases om RNA nucleotides have paired up with the bases on the dna strand the, the rna nucleotides join together to make an ?

A

mRNA molecule

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21
Q

How many bases code for one amino acid

A

3

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22
Q

3 bases in a row is known as what

A

A triplet

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23
Q

Differnt amino acids are coded for by differnt triplets eg
TAT=
AGT=

A

Tyrosine
Serine

24
Q

What are mutations

A

Changes to the base sequence of DNA

25
Q

How does mutation work (substitution)

A

One base can be swapped for another
This can cause a triplet to change
So mutation can change the amino acids in the protein that the gene codes for
A change in amino acids can cause a differnt protein to be produced
Sometimes the change in protein can be harmful

26
Q

How often do mutations happen

A

Spontaneously

27
Q

How can frequency of mutations be increased

A

Mutagenic agents

28
Q

Examples of mutagenic agents

A

UV radiation in sunlight

29
Q

How can mutations cause cancer

A

As cell division is controlled by proteins.
If mutations occur in the gene for these proteins, they can alter the proteins so they no longer work.
This can lead to the uncontrolled cell divison, and the development of a tumour

30
Q

How can mutations cause genetic disorders

A

Mutations that result in altered genes and proteins can be inherited

31
Q

Where is DNA. Found

A

In chromosomes in nucleus of eukaryotic cells

32
Q

How many genes in each human chromosomes

A

Between a couple hundred and a few thousands

33
Q

How many pairs of chromosomes do humans have

A

23pairs (46 in total)
One from each pair comes from your mother and one from your farther

34
Q

T or f
All chromosomes in a pair are the same size and carry the same genes, they are known as homologous pairs

A

F
There is an exception of X and Y sex chromosomes

35
Q

Do chromosomes in a homologous pair usually have differnt alleles

A

Yes

36
Q

What is an X shaped chromosomes

A

One chromosomes attached to an identical cop of itself.
Not homologous pairs - only shaped just after the DNA has been replicated

37
Q

Each side of an x-shaped chromosome is known as what ?
What is the area in the middle known as

A

Chromatid
Centromere

38
Q

When is mitosis needed

A

For growth and repair
If you have damaged tissue, the cells around the damaged area divide by mitosis to replace damaged cells

39
Q

Does asexual reproduction involve mitosis or meiosis

A

Mitosis

40
Q

What is asexual reproduction

A

A single organism produces offspring by dividing into two organisms or by splitting of a piece of itself

All the offspring are genetically identical

The cells divide by mitosis

41
Q

How many stages is mitosis split into

A

4

42
Q

What are the 4 stages of mitosis

A

Prophase
Metaphase
Anaphase
Telophase

43
Q

What is the period before mitosis starts called

A

Interphase

44
Q

Interphase

A

Before the cell starts to divide every DNA molecule (each chromosome) Must replicate to let each new cell has a full copy of DNA. The new molecule remains attached to the original one at the centromere

45
Q

Prophase

A

Mitosis can now begin, each DNA molecule becomes supercoiled and compact
Each Kromozone can now be seen with a light microscope and appears as two chromatids lying side by side, joined by the centromere

46
Q

Metaphase

A

The nuclear membrane breaks down and chromosomes lineup along the equator of the cell

47
Q

Anaphase

A

The centromere split in the chromatids separate, and are dragged to opposite ends of the cell

48
Q

Telophase

A

The nuclear membrane forms around each set of chromatids and the cytoplasm divides

49
Q

Does sexual reproduction involve mitosis or meiosis

A

Meiosis

50
Q

What is sexual reproduction

A

The offspring are genetically differnt from their parents and from each other. This produces variation in a population.

Each parent produces sex cells (gametes) containing just one set of genetic material- involves meiosis

During fertilisation the nuclei of the gametes join together to form a zygote

Zygote grows by simple cell division to form an embryo

51
Q

Gametes only have one set of genetic material so are described as what?

A

Haploid

52
Q

Zygote has two complete sets of genetic material so is described as?

A

Diploid

53
Q

Where does meiosis take place

A

Testes
Ovaries

54
Q

Examples of gametes

A

Sperm
Eggs

55
Q

Explain meiosis

A

The DNA replicates, so each other 46 chromosomes becomes to Chromatids joined by a centromere

  1. Chromosomes sort themselves into 23 Homologous pairs then the pairs separate. One of each pair goes to one side of the cell, and one goes together.

The cytoplasm now divides each of the new cells contain 23 chromosomes.

In both of these new cells, the chromatids separate and the cytoplasm divides to form two cells

At the end of meiosis, four haploid cells have been produced from every original diploid cell

Biology - BW (8 decks)

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