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DNA and RNA Flashcards

1
Q

What is heredity?

A

The passing on of characteristics or traits from one generation to the next.

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2
Q

What is a gene?

A

A short region of a chromosome that contains a code for the production of a protein.

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3
Q

What is gene expression?

A

The process by which the code in DNA is used to make a protein.

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4
Q

Why are some genes longer than other genes?

A

Due to the fact that proteins can be of different lengths/sizes.

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5
Q

What is coding DNA?

A

The stretch of DNA where a gene is located. It is so called because it contains the code for the production of a protein.

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6
Q

What is non-coding DNA?

A

DNA that is not responsible for producing any proteins.

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7
Q

What was non-coding DNA previously called?

A

Junk DNA.

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8
Q

What new functions of non-coding DNA have been discovered?

A

It is known that some stretches of non-coding DNA function as regulators for gene expression. They control which genes are expressed and the frequency with which they are expressed. They function by turning genes ‘on’ or ‘off’.

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9
Q

How many genes are estimated to be in the human genome?

A

Approx. 30,000.

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10
Q

In what two shapes can chromosomes be in?

A
  • Circular (as in bacteria).
  • Linear (as in multicellular organisms).
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11
Q

What is the structure of chromosomes?

A

Each chromosome is a highly coiled structure composed of a very long molecule of DNA and many millions of separate molecules of protein.

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12
Q

What are histones and what is their function?

A

Histones are a type of protein found in chromosomes and they function in stabilising the DNA and keeping it organised.

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13
Q

Why would DNA break without the associated proteins?

A

DNA is such a long and slender molecules that without the associated proteins it would easily break into much smaller pieces.

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14
Q

In any one chromosome, what percent of it is DNA?

A

40%

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15
Q

In any one chromosoe, what percent of it is protein?

A

60%

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16
Q

When mitosis is not occuring, what form is DNA in?

A

Chromatin (uncoiled DNA).

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17
Q

How are duplicated chromosomes formed from DNA and proteins?

A

The DNA first replicates itself (at the end of interphase) and is wound around the histones, which in turn go through a series of supercoiling steps to give the familiar structure of a duplicated chromosome.

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18
Q

How many pairs of chromosomes are there in a human diploid cell?

A

23 pairs.

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19
Q

What are the first 22 pairs of chromosomes called in a human diploid cell, and what are they responsible for?

A

Autosomal chromosomes (autosomes). Autosomes are responsible for controlling many different chracteristics in humans.

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20
Q

What is the 23rd pair of chromosomes called in a human diploid cell?

A

The sex chromosomes.

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21
Q

What are the two types of sex chromosome?

A

X and Y.

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22
Q

Which of the X and Y chromosomes is longer?

A

X chromosome.

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23
Q

What are the two possibilities of the sex chromosomes?

A
  • XX (female)
  • XY (male)
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24
Q

What are the two types of nucleic acid?

A
  • DNA (deoxyribonucleic acid)
  • RNA (ribonucleic acid)
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25
What does DNA consist of?
DNA consists of two strands of (double-stranded) attatched together by molecules called bases. DNA is twisted around itself to produce a shape called a double helix.
26
What are the four nitrogenous bases found in DNA?
Adenine (A), Thymine (T), Cytosine (C) and Guanine (G).
27
In what way do the four nitrogenous bases go together and why?
Adenine will always be found oppoite thymine, and cytosine will always be found opposite guanine. They pair because of their size and shape. The molecules fit snugly together, much like the pieces of a jigsaw.
28
What was achieved in the human genome project?
The entire sequence of bases in the human genome was recorded.
29
How many base pairs, on average, does each chromosome contain?
130 million base pairs.
30
What are the two strands of DNA composed of?
Phosphates and sugar molecules. Each strand is composed
31
What is the sugar molecule in DNA?
The sugar is a five carbon sugar called deoxyribose.
32
What are the two strands of DNA linked by?
Nitrogenous bases.
33
How do the nitrogenous bases join together?
The bases join to eachother by hydrogen bonding, which holds the strands together. Hydrgen bonds are very weak, but are very strong collectively.
34
How many hydrigen bonds are btween an adenine and thymine?
Two (A=T).
35
How many hydrogen bonds are there between a cytosine and a guanine?
Three (C≡G).
36
What is a nucleotide?
Consists of a sugar molecule binded to a phosphate group and a nitrogenous base
37
What is complementary base pairing?
Bases pairing up with eachother in a consistent way.
38
What group of biomolecules does adenine and guanine belong to?
Purines.
39
What is an example of an everyday purine?
Caffeine.
40
What group of biomolecules does thymine and cytosine belong to?
Pyrimidines.
41
When does DNA replication occur?
Towards the end of interphase, when the cell is preparing for mitosis.
42
# 4 steps What is the mechanism of DNA replication?
1. Double helix unwinds 2. An enzyme then opens the two strands, much in the same way a zip works. It does this by breaking the hydrogen bonds. The bases on the two strands of DNA are then exposed. These act as the template for the production of a new strand. 3. New nucelotides, which enter from the cytosol are connected to the exposed bases on the 'old' strand. The new nucleotides each contain one of the four nitrogenous bases and are attatched, so that the base pairing occurs between the bases of the old and new strands. 4. The assembly of the new strands is carried out by the anabolic enzyme, DNA polymerase.
43
What does each new chromosome consist of?
One old strand of bases and one new strand.
44
What happens once DNA replication has finished?
The DNA re-associates itself with histones and rewinds, recoils and supercoils into chromosomes. The duplictaed chromosomes stay attatched in readiness for mitosis.
45
Why is DNA replication significant?
It allows for cell continuity.
46
What is cell continuity?
The process of cells arising from cells of the same type.
47
How does variation develop in a species?
DNA replication is usually a very accurate process, however, occasionally mistakes occur and the sequence of bases changes. This is how variation develops in a species.
48
What is DNA profiling?
A method of producing a unique pattern of bonds from the DNA of a person so that it can be used for identification purposes.
49
What is needed to get a DNA profile of a person?
A tissue sample.
50
What different types of tissue samples can be used for DNA profiling?
A hair follicle, blood smear or bodily fluid.
51
What are the applications of DNA profiling?
It is used in scientific research to identify certain species and is used in medicine an din criminology/forensics.
52
What are the four steps of DNA profiling?
1. DNA isolation 2. Cutting 3. Separation 4. Pattern analysis
53
What is the process of DNA isolation?
The DNA is extracted from the cell using a type of detergent. The cell membrane is composed of a type of lipid (phospholipid) and lipids dissolve easily in detergents. When the cell and nuclear membranes are broken, the DNA is released.
54
What is the process of cutting?
Chromatin is 'cut' into fragments using an enzyme, called a restriction enzyme. Restriction enzymes cut DNA at a specific base sequence. Wherever the base sequence occurs, the DNA will be cut.
55
What is the process of separation?
A process called gel elctrophoresis is used to separate fragments based on their lengths. Gel elctrophoresis is a process in which DNA samples are placed into a porous gel and electrical current is applied. An electric field is produced, and as DNA is a negatively charged molecule, it is attracted to the positive end of the electrical field. DNA samples begin to move across the gel towards the positive end and are separated out based on their length.
56
What is the process of pattern analysis?
Gel is stained and viewed under UV light. A pattern is seen and a DNA profile can be compared to another DNA profile to see if there are similarities or differences.
57
What is genetic screening?
A test of a person's DNA to see if an altered or mutated gene is present. Often carried out when it is suspected that a person is carrying an altered gene, which may give rise to a genetic disease.
58
What are some common genetic dseases that occur in Ireland?
* Cystic fibrosis (where there is a build up of mucus in the lungs). * Haemochromatosis (where there is a build up of iron in the body).
59
Where is RNA mostly found?
Mostly found free in the cytoplasm in the form of ribosomes. However, it can also be found in the nucleus.
60
What are ribosomes composed of?
RNA.
61
What is the structure of RNA?
RNA is single stranded, meaning it is composed of one strand.
62
What bases does RNA have?
Cytosine (C), guanine (G), adenine (A) and uracil (U).
63
What sugar does RNA have?
Ribose.
64
How is RNA made?
RNA is made using the code in DNA. Therefore, the code RNA carry is complimentary to a DNA code.
65
What enzyme produces RNA?
RNA polymerase.
66
What is the function of RNA?
RNA goes on to function in protein synthesis.

Biology (16 decks)

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