C5 Flashcards

(50 cards)

1
Q

DNA is…

A
  • Deoxyribonucleic acid
  • Double-stranded molecule
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2
Q

Structure of DNA
Nucleotide Structure
Base pairs

A

Refer to: Student version - DNA Replication, Slides 11 and 12

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3
Q

Why is DNA Replication Considered Semi-Conservative?

A

Each new DNA molecule is made up of one old ‘conserved’ strand, and one new strand

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4
Q

What are the 4 Enzymes Involved in DNA replication?

A

Helicase - ‘unzips’ double-stranded DNA by breaking
hydrogen bonds

Primase - Builds starting Primer

DNA Polymerase - Forms new DNA strands

Ligase - connects segments to form one strand

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5
Q

Process of DNA replication + what enzymes: STEP 1

A
  • Double-stranded DNA molecule is ‘unzipped’ into 2 stands

Enzyme: helicase
- breaks hydrogen bonds between base pairs to separate two strands
- There are now 2 template strands

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6
Q

Process of DNA replication + what enzymes: STEP 2

A

-Primer Binding

Enzyme: Primase
- synthesises a small RNA primer which acts as a kick-start the process

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7
Q

Process of DNA replication + what enzymes: STEP 3

A

Elongation

Enzyme: DNA polymerase
- attaches new bases to the 2 template strands

  • is the enzyme responsible for synthesising the new strands of DNA as well as correcting any errors
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8
Q

Process of DNA replication + what enzymes: STEP 4

A

No name

Enzyme: Ligase
- Connects the DNA fragments that have been added
- Forms one continuous new strand
- Removes RNA primer

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9
Q

Enzyme Structure Diagram (should include)

A

Substrate: Molecule that binds to the enzyme’s active site

Active Site: Region on the enzyme where the substrate binds

Enzyme: Biological catalyst that speeds up chemical reactions

Allosteric site: Site on the enzyme where molecules can bind to change its activity

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10
Q

What is the active site?
Induced Fit Model?

A

The place on the enzyme’s surface that is complementary to its substrate.

Induced Fit Model: The enzyme’s active site slightly conforms to the shape of the substrate

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11
Q

What are Enzymes?

What do they do?

A
  • Biological catalysts
  • Requires less energy to start reactions (Activation Energy)
  • Rate of reaction speeds up
  • Enzyme remains unchanged after the reaction
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12
Q

De-naturing

A

Denatured proteins lose their shape and function

Denaturing can occur from changes in temperature and pH level

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13
Q

Proteins: 2 types

A

Globular proteins: proteins used for cellular processes, eg. enzymes

Structural Protein: proteins used for structure, eg. hair, nails

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14
Q

Anabolic vs Catabolic Reactions

A

Anabolic: building up reactions
- Bonds between substrates are formed to
produce product
Catabolic: Breaking down reactions
- Bonds between substrates are broken to
produce product

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15
Q

2 Types of Inhibitors + what do they do?

A

Competitive Inhibition: A molecule binds to the enzyme’s active site and prevents substrate from binding

Non-competitive Inhibition: A molecule binds to the allosteric site and causes a conformational change to the enzyme’s active site.

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16
Q

Co-factors and Co-enzymes

A
  • Any non-protein chemical needed for an enzyme reaction to proceed

Organic molecules are called co-enzymes
Inorganic molecules are called co-factors

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17
Q

4 Factors Affecting Rate of Reaction With Enzymes

A
  • Temperature
  • pH level
  • Enzyme concentration
  • Substrate concentration
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18
Q

What is a Protein?
What do they do?

A
  • A protein is a complex structure (polymer) composed
    of amino acids, joined together by peptide bonds
  • They are responsible for virtually all functions in
    organisms
  • The shape of a protein determines it’s function

Added helpful info (not needed for exam):
- The synthesis of proteins is determined by the
sequence of bases in a gene
- Each gene codes for a specific protein

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19
Q

Process of Protein Synthesis: Transcription

post transcription mod

A

Enzymes bind to DNA and unwind the double helix to expose the gene to be transcribed
- this is the template strand

The RNA polymerase moves along the gene, producing an mRNA strand
- Moves to ribosome for next stage
- Introns removed to create the mature strand

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20
Q

Process of Protein Synthesis: Translation

A

The mRNA exits the nucleus and docks onto a ribosome in the cytoplasm.
- ribosome contains a unit that reads (translates) each codon
- The translation starts when the ribosome reads the ‘start’ codon
- the tRNA brings the complimentary anticodon
- the tRNA carries the correct amino acids
- The amino acids bond via peptide bonds and form a polypeptide chain

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21
Q

Prokaryotic Gene Expression
What is the Lac Operon
How is it regulated

A

A group of genes with a single promoter that codes for the breakdown of lactose in E. coli bacteria

  • The lac operon is regulated by the presence or absence of lactose
22
Q

Gene Expression - Lac Operon (2 main components)

A

Promoter - the region of DNA where the RNA polymerase enzyme binds
- Gene regulation begins at the promoter

Operator - Segment of DNA between promoter and genes. Acts as a switch.
- When the repressor protein (Lac I) binds to the operator, it blocks transcription from occurring.

23
Q

Genes Involved in Lactose Metabolism (3) + drawing

A

Lac Z: gene with code to make lactase (breaks down lactose)
Lac Y: increases membrane permeability
Lac A: Codes for a second enzyme that helps with the first enzyme

Refer to: Student Pro Gene expression and regulation - Slide 2 for drawing

24
Q

Why is it Beneficial To Only Express Genes When They’re Needed?

A
  • It saves energy for the other important cellular functions.
  • prevents overproduction
25
2 components of DNA (Introns + Exons)
Introns: Non-coding regions of DNA and mRNA Exons: Coding regions - Introns are removed from the mRNA strand as they do not produce proteins. - A mature mRNA strand has had the introns removed and the remaining exons joined together
26
Process in the Lac Operon when Lactose is Absent?
The repressor protein binds to the operator. This prevents RNA polymerase from transcribing the structural genes.
27
Process in the Lac operon when lactose is present?
- When lactose is present, it binds to the repressor protein - This stops the repressor from binding to the operator This results in the conformational change to the repressor, meaning it is no longer complementary to the operator - Allows RNA polymerase to transcribe structural genes
28
What is a mutation?
A change in the sequence of the nucleotides of a genome
29
3 Types of Mutations
Point mutations Block Mutaions Cromosonal Mutations (not in C5)
30
What are block mutations (chromosomal) + 4 types
Is when a larger section of a chromosome is changed Duplications: Part is copied, can cause extra gene expression Deletions: Part is deleted, those genes not expressed Inversions: A segment removed and replaced in reverse order Translocations: A part of one chromosome added to another
31
Point Mutations (2 types)
Change of one base Insertion/deletion: eg. ATGC becomes ATC Substitution: eg. ATGC becomes ATAG
32
Effects of Point Mutations (3)
Silent: the changed base does not alter the amino acid sequence, changed triplet codes for some amino acid e.g. GAG mutates to GUG Missense: the changed base alters a single amino acid Nonsense: the changed base leads to a premature 'stop' codon - The polypeptide chain will end prematurely and is likely dysfunctional
33
Mutagens
E.g., ionising radiation, heat, UV rays, X-rays, and chemical damage. Mutagens are agents that induce genetic mutations they disrupts the normal structure and function of DNA Mutations can also occur spontaneously
34
What are the inputs + outputs of photosynthesis
Inputs: carbon dioxide + water Outputs: Glucose + oxygen Equation: 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂ * equation is not a must know but helpful
35
What are the two stages of photosynthesis?
Light dependent - first stage - involves splitting of water molecules using light energy Light Independent - second stage - CO₂, ATP and H+ used to create glucose
36
chlorophyll...
- absorbs light energy in photosynthesis - found in thylakoid membrane
37
Light Dependent - Stage 1 phts
- Occurs in thylakoid membrane - When light energy is captured, it splits 12 water molecules (phytolosis), producing 6 oxygen molecules, H+ ions and electrons - Oxygen released by diffusion out of the chloroplast, out of cell, and into atmosphere. - Enzyme reactions result in H+ ions and created ATP molecules being transported from thylakoid to stroma, where they are used next stage
38
Light Independent - Stage 2 phts
- Occurs in stroma - Involves the synthesis of glucose from carbon dioxide. - Enzyme reactions take 6 CO₂ molecules from atmosphere, plus the ATP and H+ and forms one molecule of glucose
39
Factors affecting rate of photosythesis (3)
Temperature - Higher temp = higher rate (until a certain point) - As temp increases, the enzymes gain kinetic energy and therefore catalyse at a great rate - at approximately 45 degrees, the enzymes begin to denature so rate of phts decreases CO₂ concentration - higher CO₂ conc = higher rates until certain point - increase in reactant concentration - at high CO₂ concentration, rate levels off as enzymes are saturated Light intensity - higher light intensity = higher rate until a point - more light can be trapped by the chloroplasts to provide energy to drive photosynthesis. - At high light intensities, rate levels off as max amount of light is already trapped
40
Structure and Function of Chloroplasts
Chloroplast - membrane-bound organelle - Contains stacks of thylakoids - Each stack of thylakoids is called granum (plural = grana) - chlorophyll is embedded in the thylakoid membranes, and absorbs light energy - The more thylakoid membranes there are, the more surface area available for capturing light energy. - remaining space in chloroplast is filled with stroma
41
Inputs and outputs of cellular respiration?
Inputs: Glucose + Oxygen Outputs: Carbon dioxide + Water Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36-38 ATP * equation is not a must know but helpful
42
Stages of Cellular Respiration Overview
Refer to the Respiration PowerPoint - Slide 8
43
Anaerobic Cellular Respiration Add differences between plants and animals
Fermentation - can break down glucose without oxygen but is less efficient - After glycolysis, there is two pyruvate and NADH - The NADH loses its hydrogen - this converts the pyruvate into lactic acid (animals) or ethanol (plants) - occurs in cytosol
44
Role of Mitochondria in Aerobic Respiration
Matrix: Fluid component of mitochondria, the site of the Krebs Cycle Cristae: folds of inner membrane that project into matrix, site of Electron Transport Chain (ETC) * more cristae = more surface area = more reactions in ETC = more ATP produced
45
Stage 1 Respiration - Glycolysis (how many ATP)
- Occurs in cytosol - Breaks down large glucose molecule into two smaller pyruvate molecules and H+ ions -Thes pyruvate and H+ ions can now be transported into the mitochondria - produces 2 ATP * no O₂ required for glycolysis
46
Stage 2 Aerobic Respiration - The Krebs Cycle + ATP
- Follows glycolysis - second stage of aerobic respiration - Occurs in fluid matrix of mitochondria using pyruvate from glycolysis Produces: - 2 ATP - CO₂ - diffuses out of the cell - FADH₂ and NADH - co-enzymes carrying H+ ions
47
Stage 3 Aerobic Respiration - Electron Transport Chain
3rd stage of aerobic respiration - Occurs in the cristae - Uses H+ supplied from Krebs Cycle - Series of steps involving transport of H+ ions and use of the enzyme ATP Synthase to make ATP *Produces 32-34 ATP molecules *O₂ needed
48
Factors affecting rate of respiration
- increasing reactant concentration (glucose, O₂) increases rate (until enzymes are saturated) - Temperature can speed up or slow down rate - pH level can alter enzyme activity, and therefore affect rate
49
ATP
When cells need energy, the bond between the second and third phosphate is broken. - molecule is then Adenosine Diphosphate - ADP then attaches to phosphate forming ATP again - Continues in a cycle
50
What are Endonucleases