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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
How does mutation work (substitution)
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
How often do mutations happen
Spontaneously
27
How can frequency of mutations be increased
Mutagenic agents
28
Examples of mutagenic agents
UV radiation in sunlight
29
How can mutations cause cancer
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
How can mutations cause genetic disorders
Mutations that result in altered genes and proteins can be inherited
31
Where is DNA. Found
In chromosomes in nucleus of eukaryotic cells
32
How many genes in each human chromosomes
Between a couple hundred and a few thousands
33
How many pairs of chromosomes do humans have
23pairs (46 in total) One from each pair comes from your mother and one from your farther
34
T or f All chromosomes in a pair are the same size and carry the same genes, they are known as homologous pairs
F There is an exception of X and Y sex chromosomes
35
Do chromosomes in a homologous pair usually have differnt alleles
Yes
36
What is an X shaped chromosomes
One chromosomes attached to an identical cop of itself. Not homologous pairs - only shaped just after the DNA has been replicated
37
Each side of an x-shaped chromosome is known as what ? What is the area in the middle known as
Chromatid Centromere
38
When is mitosis needed
For growth and repair If you have damaged tissue, the cells around the damaged area divide by mitosis to replace damaged cells
39
Does asexual reproduction involve mitosis or meiosis
Mitosis
40
What is asexual reproduction
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
How many stages is mitosis split into
4
42
What are the 4 stages of mitosis
Prophase Metaphase Anaphase Telophase
43
What is the period before mitosis starts called
Interphase
44
Interphase
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
Prophase
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
Metaphase
The nuclear membrane breaks down and chromosomes lineup along the equator of the cell
47
Anaphase
The centromere split in the chromatids separate, and are dragged to opposite ends of the cell
48
Telophase
The nuclear membrane forms around each set of chromatids and the cytoplasm divides
49
Does sexual reproduction involve mitosis or meiosis
Meiosis
50
What is sexual reproduction
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
Gametes only have one set of genetic material so are described as what?
Haploid
52
Zygote has two complete sets of genetic material so is described as?
Diploid
53
Where does meiosis take place
Testes Ovaries
54
Examples of gametes
Sperm Eggs
55
Explain meiosis
The DNA replicates, so each other 46 chromosomes becomes to Chromatids joined by a centromere 46. 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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