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Stage 2 Biology > Topic 1: DNA & Proteins > Flashcards

Topic 1: DNA & Proteins Flashcards

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1
Q

What are the four bases that make up DNA?

A

Adenosine
Thymine
Cytosine
Guanine

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2
Q

What are the base pairings in DNA?

A

Adenosine (A) - Thymine (T)

Cytosine (C) - Guanine (G)

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3
Q

What are the differences between DNA and RNA?

A

DNA is double-stranded, RNA is single stranded
DNA has Thymine (T) nucleotide, RNA has Uracil (U)
DNA Sugar is Deoxyribose, RNA sugar is ribose

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4
Q

What is the structure of a nucleotide?

A

Phosphate – Sugar – Base

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5
Q

What are the 4 types of RNA?

A
  1. mRNA - Messenger
  2. tRNA - Transfer
  3. rRNA - Ribosomal
  4. Ribozymes
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6
Q

Explain the steps involved in DNA Replication:

A
  1. Weak Hydrogen Bonds of DNA are overcome - Strands separate
  2. Free nucleotides bind to complementary nucleotides on original strands
  3. DNA Polymerase binds sugar-phosphate backbone, forming new strand
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7
Q

Why is DNA Replication Semi-Conservative?

A

Each of the double strand of DNA - One has been conserved from the parent.

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8
Q

What are genes?

A

Segment of DNA that code for either proteins or RNA molecules

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9
Q

Describe Transcription and the steps involved:

A

The process of converting DNA into mRNA.

  1. Gene of interest unwinds and unzips
  2. Free RNA nucleotides bind to complementary bases on Template Strand of DNA
  3. RNA Polymerase binds nucleotides together - forming mRNA
    * Eukaryotic Cells undergo RNA Splicing
    * Prokaryotic Cells - mRNA is immediately useable.
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10
Q

Describe Translation and the steps involved:

A

mRNA is used to assemble a protein

  1. mRNA arrives at the ribosomes and situates itself between the two subunits.
  2. tRNA molecules carrying specific amino acids bind via their anti-codons to complementary codons on mRNA
  3. Adds amino acids to the growing polypeptide chain in the correct order which folds to form the final protein.
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11
Q

What are the four structures of a protein?

A
  1. Primary
  2. Secondary
  3. Tertiary
  4. Quaternary
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12
Q

What is the primary structure of a protein?

A

Linear Chain of amino-acids

Is determined by the sequence of amino-acids

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13
Q

What is the secondary structure of a protein?

A

Determined by coiling of parts of polypeptide into Alpha Helix and Beta Pleated Sheets.

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14
Q

What is the tertiary structure of a protein?

A

Final three-dimensional structure of entire polypeptide

*Structure influences overall function

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15
Q

What is the Quaternary Structure?

A

Two or more polypeptides

Example: Hemoglobin

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16
Q

What are enzymes?

A

Globular Proteins that act as biological catalysts which reduce activation energy and in turn speed up metabolic reactions.

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17
Q

Describe the structure of enzymes:

A

Three-dimensional structure of enzyme is determined by its unique amino-acid sequence
Active Site: Complementary to specific substrate

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18
Q

Describe the Induced-Fit Model:

A

Substrate slightly changes the shape of the active site of the enzyme, which puts pressure on the bonds and hence lowers activation energy.

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19
Q

How does temperature impact enzyme activity?

A

Low Temp:
- Less Kinetic Energy, therefore fewer collisions between enzyme and substrate (Activation energy is less likely to be reached)
- Hence, enzyme activity is decreased
High Temp:
- Enzymes denature - can no longer bind to its substrate

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20
Q

How does concentration impact enzyme activity?

A

Increase: result in an increase in enzyme activity until all active sites are occupied.
Become Saturated

21
Q

How do competitive inhibitors affect enzyme activity?

A

Have Shape complementary to the active site of the enzyme

Prevent Substrates from binding

22
Q

How do non-competitive inhibitors affect enzyme activity?

A

Bind elsewhere on the enzyme, causing a permanent change to the active site of the enzyme.
Decreases Enzyme activity

23
Q

What is gene expression?

A

Turning genes on or off

controls cellular differentiation

24
Q

What does phenotype refer to?

A

The observable and biochemical traits of an individual

25
Q

What is Epigenetics?

A

Long-term changes in gene expression

No change in the DNA sequence

26
Q

What are transcription factors?

A

Allow/Block transcription into mRNA

27
Q

What are translation factors?

A

Increase/Decrease translation of mRNA

28
Q

What is DNA methylation?

A

Addition/removal of methyl group to cytosine nucleotide

Can both activate and deactivate genes

29
Q

How does Epigenetics cause cancer?

A

Cancer is uncontrolled cell division
Deactivation of tumour-suppressor genes - uncontrolled cell division
Activation of oncogenes - excessive cell division and growth, therefore cancer

30
Q

What are mutations?

A

Cause permanent changes in the DNA sequence

31
Q

What are the factors that induce mutations?

A 
Temperature 
Ionising Radiation (xRays, Gamma Rays) 
Mutagenic Chemicals (change molecular structure of DNA) 
Viruses (insert oncogenes into genomes of host cells)
32
Q

What are the two main types of mutations?

A
  • Substitution: less deleterious

- Deletion: more deleterious - causes frameshift

33
Q

What are germinal mutations?

A

Can be inherited by offspring

rarely cause observable changes in individual

34
Q

What are somatic mutations?

A

Cause observable changes to the phenotype of the individual

Are not passed onto offspring

35
Q

What is PCR and what are its requirements?

A 
Process used to amplify DNA 
Requirements: 
- Target DNA 
- Primers (short single strand of DNA) 
- Free DNA nucleotides 
- Heat-resistant DNA Polymerase (normal will denature at high temperatures)
36
Q

What are the steps involved in PCR?

A
  1. DNA strands are separated using heat
  2. DNA is cooled, allowing primers to bind to complementary base pairs on the separated strands of DNA
  3. DNA Polymerase and free DNA nucleotides synthesise complementary DNA strand
  4. Heating and Cooling is repeated many times - creating millions of copies
37
Q

What is Gel Electrophoresis and describe how it works:

A

Separation of DNA fragments into different lengths.

  1. DNA is loaded into wells & dye is added
  2. Electrical charge is passed through the gel
  3. DNA is negatively charged - migrate to the positive end
  4. Smaller fragments of DNA are able to move more easily
38
Q

What are STR’s (Short Tandem Repeats) ?

A

Non-coding regions of DNA
Small Sections - typically 2-5 nucleotides long
*Each Person has a unique no. of STR’s

39
Q

What are some of the pros and cons with genetic collection?

A

Pros:
- Identification of genetic diseases before symptoms show
- Prevent false labelling of produce
- Increased crime fighting efficiency
Cons:
- Testing can be done without consent
- Public databases can share sensitive information
- Insurance costs may increase for people with genetic diseases

40
Q

What are the two processes involved in producing GMO’s?

A
  • Transgenics (use of recombinant DNA)

- CRISPR

41
Q

What is the procedure involved in creating recombinant DNA?

A
  1. Extract DNA from cells
  2. Select Gene - Using Gene Probe - radioactively labelled
  3. Remove Gene - Using Restriction Enzymes (same RE must be used)
  4. Transfer DNA into different organism
42
Q

What are some ways of transferring DNA into a different organism?

A
  • Micro-injections
  • Viral Vectors
  • Electroporation
  • Bacterial Transformation
43
Q

How are micro-injections used to transfer DNA?

A
  • DNA is physically injected inside the cell (micro-pipette)
44
Q

How are viral vectors used in transferring DNA?

A
  • viral genetic information is removed, DNA is then placed inside
  • Virus invades host cells - DNA incorporates itself into host DNA
45
Q

What is electroporation?

A

The use of electricity to create pores on the surface of the cell membrane, allowing DNA to enter

46
Q

What is Bacterial Transformation?

A
  • The use of heat shock which creates temporary pores in the cell membrane
    Allows transformed plasmid DNA to enter
47
Q

What is CRISPR?

A

Fast and reliable gene editing technology that involves guide RNA and Cas 9 proteins.

48
Q

How does CRISPR work?

A
  1. guide RNA is attached to target DNA
  2. guide RNA takes Cas-9 protein to target DNA
  3. Cas-9 cuts DNA at that specific location
  4. Results in a gene ‘knockout’, target DNA will no longer work
    * Template strand of DNA can be added to ‘CRISPR Cocktail’ which acts as a guide for repair.
49
Q

What is protein design and what are its possible applications?

A

Protein Design involves artificially creating proteins.
Artificial gene and amino-acid sequence must be created
Possible Applications:
- Drug Delivery
- Novel Vaccines

Stage 2 Biology (4 decks)

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