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Biology > Chapter 6: Nucleic Acids & Protein Synthesis > Flashcards

Chapter 6: Nucleic Acids & Protein Synthesis Flashcards

1
Q

What are the 4 topics under this unit?

A
  1. Structure and function of nucleic acids
  2. DNA replication
  3. Protein Synthesis
  4. Mutation
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2
Q

What is a nucleotide composed of?

A
  • Phosphate group
  • Pentose sugar
  • Nitrogenous base
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3
Q

What are the bonds between neighbouring nucleotides and what is the bond between base pairs?

A
  • Between nucleotides: Phosphodiester bond

- Between base pairs: Hydrogen bond

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4
Q

Name the 5 kinds of nitrogenous bases and identify which base pairs together

A
  • Adenine & Thymine
  • Guanine & Cytosine
  • Uracil & Adenine
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5
Q

How many rings does a purine have? Which nitrogenous bases are purines?

A
  • 2 rings

- Guanine & Adenine

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6
Q

How many rings does a pyrimidine have? Which nitrogenous bases are pyrimidine?

A
  • 1 ring

- Cytosine, Uracil & Thymine

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7
Q

Differenciate between RNA and DNA

A
  • RNA is usually single-stranded while DNA is usually double-stranded // double-helix structure
  • RNA has a ribose sugar while DNA has a deoxyribose sugar
  • RNA has URACIL while DNA has THYMINE
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8
Q

What are 3 examples of polynucleotides?

A

RNA
DNA
ATP

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9
Q

Identify 3 kinds of RNA and state their function

A

mRNA: transfers replicated genetic information to ribosomes for protein synthesis

rRNA: forms ribosomes, needed for protein synthesis

tRNA: brings amino acids from the cytoplasm to the ribosomes to create proteins

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10
Q

What is ATP composed of?

A
  • 3 phosphate groups
  • Adenine molecule
  • a Ribose sugar
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11
Q

What is the function of ATP?

A

Used as the energy “currency” of the cell; provides energy needed for work

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12
Q

State the name for the model on how DNA is replicated and explain what it means.

A
  • Semi-conservative

- Half of each DNA molecule contains 1 strand of the original parent DNA

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13
Q

Identify the 4 enzymes and their purposes in DNA replication

A
  1. Helicase - unwinds DNA
  2. DNA polymerase - adds base pairs to template strands and proofreads its own work
  3. Primase - adds “RNA primers” on the lagging strand that indicate to the DNA polymerase on where it should work
  4. Ligase - “glues” or joins together Okazaki fragments to the lagging strand
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14
Q

DNA is replicated in the ____ to _____ direction

So the leading strand is in the ___ to ___ direction

A

5’ –> 3’ direction

3’ –> 5’ direction

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15
Q

Why is DNA antiparallel?

A

This arrangement allows for complementary nucleotide bases to pair with one another

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16
Q

Define gene

A

A sequence of nucleotides that composes part of a DNA molecule that codes for a polypeptide // protein

17
Q

What is a codon?

A

Series of 3 nucleotides in a DNA molecule that codes for 1 amino acid

18
Q

State 3 characteristics of codons and what it means.

A
  • UNIVERSAL: same for all organisms; can be read by all organisms
  • REDUNDANT // DEGENERATE: some codons code for the same amino acid, which protects the body from mutations
  • NON-OVERLAPPING: each triplet is separate from other triplets; each triplet is strictly 3 nucleotide bases
19
Q

State 2 stages of Protein Synthesis

A
  1. Transcription (DNA –> RNA)

2. Translation (mRNA –> Proteins)

20
Q

State the 4 stages of Transcription and outline what happens at each stage

A
  1. INITIATION: RNA polymerase attaches to a region of DNA called the “Promoter”
  2. ELONGATION: Strands separate and RNA polymerase begins to form a strand of complementary nitrogenous bases to the template strand
  3. TERMINATION: newly-synthesized RNA strand is detached from original DNA molecule and DNA returns to its double-helical structure
  4. POST-TRANSCRIPTIONAL MODIFICATION: Addition of Guanine to the start, Addition of 100 Adenine nucleotides to the tail, removal of introns
21
Q

What are introns?

A

The non-coding components of a DNA or RNA strand

22
Q

Why are 100 adenine molecules added to the mRNA during transcription?

A

It serves as protection from breakdown by nucleases

23
Q

Outline 5 stages of translation

A
  1. AMINO ACID ACTIVATION: amino acids bind with tRNA through the usage of ATP. ATP will also be used later on to form peptide bonds with other amino acids.
  2. ATTACHMENT TO RIBOSOME: mRNA strand binds to the ribosome.
  3. tRNA: tRNA (each with their own amino acid) will bind with sites found on the ribosome (P -> A -> E) based on the anticodon of tRNA being complementary to the codon found on the mRNA.
  4. MOVEMENT OF RIBOSOME: After neighbouring amino acids are bonded together via, peptide bonds, to form a strand, the ribosome moves further along the mRNA strand, releasing amino acids found on the E-site, and allowing space for more amino acids to be bound to the ribosome.
  5. STOP CODON: When the ribosome reaches a stop codon, the polypeptide chain is released from the ribosome.
24
Q

Define Mutation

A

a random unpredictable change in DNA

25
Q

State 3 ways how mutations can arise

A
  • change in the sequences of bases of one part of a DNA molecule
  • addition of DNA or loss of DNA from a chromosome
  • change in the total number of chromosomes in a cell
26
Q

What is a point mutation?

A

Genetic mutation where a single nucleotide base is changed, deleted or inserted

27
Q

Identify and explain 3 possible effects of point mutations:

A
  1. SILENT MUTATION - mutation in DNA that does not cause a subsequent change in amino acid output
  2. MISSENSE MUTATION - mutation in DNA that results in a codon for a different amino acid
  3. NONSENSE MUTATION - mutation in DNA that causes a protein to stop//terminate earlier than expected; codes for a STOP codon
28
Q

What kind of point mutation is Sickle Cell Anaemia?

A

Substitution mutation

29
Q

What is the importance of hydrogen bonding in DNA?

A
  • Holds 2 polynucleotide strands together // prevents unwinding
  • Allows for the double-helix structure of DNA
  • Increases stability of DNA molecule
30
Q

Gene codes for _____

Codon codes for ____

A
  • Protein // polypeptide chain

- Singular amino acid

Biology (5 decks)

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