DNA to Protein I Flashcards

1
Q

Define gene

A

Section of DNA / Chromosome which codes for one or more proteins.
Some are coding and some are non - coding blocks.

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2
Q

Define gene expression

A

Genes can be switched on and off.

Genes can code for RNA too.

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3
Q

Define genome

A

An organisms entire base sequence. (found in mitochondria of every cell. )

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4
Q

Define exome

A

Part of genome which is made up of coding exons (this is the coding bit of the genome).

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5
Q

What are 4 main types of centromere localisations?

A

Metacentric = Centromere is in the middle.
Sub - Metacentric = the centromere is slightly higher than it is in metacentric formation.
Acrocentric = forms rabbit ears style formation.
Telocentric = There are no upper arms to the structure.

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6
Q

Which centromere localisation doesn’t exist in humans?

A

Telocentric

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7
Q

What are the 3 key features used to identify chromosomes?

A

1) Size
2) Banding Pattern
3) Centromere Position

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8
Q

What is the classic structure of ‘G - Banding’?

A

Classic structure of light and dark banding.
Light Band = Euchromatin
Dark Band = Heterochromatin

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9
Q

What do chromosomes usually exist as?

A

Exists as chromatin.

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10
Q

What happens to DNA during cell division?

A

DNA is complexed with various proteins and undergoes several levels of compacting via coiling and supercoiling.

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11
Q

What is DNA normally wrapped around?

A

Histones.

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12
Q

What is the structure of chromosome?

A

8 Histones

2 turns of DNA

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13
Q

What is the formation of nucleosome?

A

Octamer of Histones.

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14
Q

What does Histone H1 link to?

A

Linker DNA.

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15
Q

What is the difference between euchromatin and heterochromatin in terms of function?

A

Euchromatin allows gene expression whereas heterochromatin DOES NOT allow gene expression.

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16
Q

Explain heterochromatin in detail.

A

Inactive DNA due to NO genes present / genes aren’t expressed.
HIGHLY BOUND = No room for transcription.

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17
Q

Explain euchromatin in detail.

A

Actively expressed DNA.

LOOSELY BOUND = Allows room for transcription.

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18
Q

What is the function of centromeres?

A

Keeps sister chromatids together.
Attaches to microtubules during cell division.
Structurally intergral.

19
Q

What is the effect of having heterochromatin in the centromere structure?

A

Normally highly repetitive.

20
Q

What is the function of telomerase?

A

Repairs telomeres but is only ACTIVE in certain cell types.

= Can lead to cancer if switched on in the wrong cells.

21
Q

What happens to the structure of telomeres when they degrade?

A

They become shorter and thus, can affect the gene function and protein production.

22
Q

What are the stages in the cell cycle?

A
G0 
G1 
S
G2
Mitosis
Cytokinesis
23
Q

What happens in G1?

A

Cell makes a variety of proteins which are needed for DNA replication. (known as a single chromatid).

24
Q

What happens in G0?

A

Cell cycle arrest occurs.

25
What happens in S?
Synthesis occurs = This is where chromosomes are replicated and therefore, each chromosome consists of two sister IDENTICAL chromatids.
26
What happens in G2?
Synthesis of proteins. | Some cells don't replicate though.
27
What happens when the S - stage does not occur?
There would be a reducing number of chromosomes during cell division.
28
What is a genome?
Combinaton of alleles at a single locus.
29
What is contained within the nuclear genome?
22 pairs of autosomes. | 1 pair of sex chromosomes.
30
How are diseases passed onto children / inherited?
Mitochondrial disorders are passed down via the maternal side due to ova providing mitochondria. Always MOTHER TO CHILD.
31
What is the structure of a human mtDNA?
Circular DNA. Heavy and Light Strand. Heavy (H, outer ring) and Light (L, inner ring).
32
What is the structure of a nucleotide?
Nitrogenous Base = Adenine / Cytosine / Guanine / Thymine Phosphate Sugar = Deoxyribose
33
What are the two pyrimidines?
Cytosine | Thymine
34
How many hydrogen bonds are there between A and T?
2 hydrogen bonds.
35
How many hydrogen bonds are there between C and G?
3 hydrogen bonds.
36
What is the procedures within the Central Dogma?
DNA -> RNA = Transcription OCCURS IN THE NUCLEUS. RNA -> Protein = Translation OCCURS IN THE CYTOPLASM.
37
What are introns?
Non - Coding Section of gene between exons.
38
What is the UTR?
Contains regulatory elements which is IMPORTANT for control of protein synthesis.
39
What is the sense and antisense strand?
Sense Strand = Same sequence as the mRNA molecule. | Antisense Strand = Used as a template to generate this identical mRNA strand.
40
What is splicing?
Removing of introns.
41
How is mRNA modified after transcription?
Capped at 5' prime end. Polyadenylated at 3' prime end. Introns are removed.
42
What is mRNA?
Carries genetic information from nucleus to cytoplasm.
43
What is rRNA?
Located in the cytoplasm. | It's very important in directing translation.
44
What is tRNA?
Located in the cytoplasm. | Transfers amino acids to ribosome to generate protein.