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Genes And Health Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is another name for proteins

A

Polypeptides

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2
Q

Describe what the primary structure of a protein is

A

A linear sequence of the amino acids in a protein

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3
Q

Secondary structure is the _____________________ of parts of a _____________ due to ________ bonds between _______ bonds

A
  • regular folding
  • protein
  • hydrogen
  • peptide
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4
Q

Alpha helix is a type of ________ structure

A

Secondary

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5
Q

Alpha helixes are held together by _____________ bonds running __________ to the long ______________

A
  • hydrogen
  • parallel
  • helical axis
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6
Q

Why is alpha helix a stable and strong structure

A

Has many hydrogen bonds

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7
Q

What is a beta pleated sheet

A

Another type of secondary structure

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8
Q

A beta pleat sheet is when the polypeptide chain ___________ back and forth forming a sheet of _____________

A
  • zig-zags
  • antiparallel strands
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9
Q

Beta pleated sheets strands are held together by ____________ bonds between ____________ bonds

A
  • hydrogen
  • peptide
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10
Q

Tertiary structure is the __________________ structure of the whole protein chain formed by ________ between _____________

A
  • overall 3D
  • bonds
  • R groups
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11
Q

Hydrophobic interactions forming tertiary structures are between…

A

R groups

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12
Q

Hydrogen bonds in tertiary groups are between…

A

H and O of R groups

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13
Q

_________ in tertiary structures are between charged R groups

A

Ionic Bonds

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14
Q

S-S bonds in tertiary structures are __________ and between ______________ R groups

A
  • covalent
  • two cysteine R groups
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15
Q

Quaternary Structure is…

A

The 3D structure of several polypeptide chains interacting w/ each other via bonds between R
groups

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16
Q

What are conjugated proteins?

A
  • proteins that are joined to other non protein molecules
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17
Q

What is another name for non protein molecules

A

Prosthetic groups

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18
Q

Globular proteins have ________ structures

A

Primary, Secondary, Tertiary, Quaternary

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19
Q

Fibrous Proteins have ______________ structure

A

Primary, Secondary, Quaternary

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20
Q

Globular proteins have a _____________________ shape

A
  • small spherical and compact
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21
Q

Why are globular proteins soluble?

A

They have hydrophillic R groups outside

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22
Q

Examples of Globular proteins

A

-Enzymes
-Antibodies
-Hormones

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23
Q

What is the shape of fibrous proteins?

A
  • Large long strong fibres
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24
Q

Fibrous proteins are insoluble as ________________

A

Hydrophobic R groups are on the outside

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25
Q

Fibrous proteins have __________ roles

A
  • Structural
  • collagen, keratin
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26
Q

How are peptides made

A

Condensation

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27
Q

How are peptides broken

A

Hydrolysis

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28
Q

What happens when amino acids are dissolved in water?

A
  • They become Zwitterions
  • hydrogen gained on N terminus
  • hydrogen lost on C terminus
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29
Q

what effects does cystic fibrosis have on the respiratory system?

A
  • lung infections
  • breathing problems
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30
Q

What effects does CF have on the digestive system

A
  • impaired digestion
  • damage to pancreas
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31
Q

C.F can cause _____________ in the reproductive system

A

Infertility

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32
Q

Cystic fibrosis can cause sweat to become…

A

Very salty

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33
Q

What does the plural membrane do?

A

Prevent friction between lungs and ribs

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34
Q

Name two components of the trachea

A
  • smooth muscle ( not under conscious control )
  • cartilage ring ( keeps it open)
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35
Q

Mucus is produced by __________ cells which are located between ______________________ lining ________ tract

A
  • goblet
  • ciliates epithelial cells
  • respitory
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36
Q

The trachea, bronchi and bronchioles contain:

A
  • goblet cells
  • ciliated cells
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37
Q

Terminal bronchioles only contain:

A
  • ciliated cells
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38
Q

Why are there no goblet/ciliated cells in the alveoli?

A
  • they would reduce gas exchange
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39
Q
A
  1. Cilia
  2. Mucus
  3. Goblet cell
  4. Columnar epithelial cell
  5. Basement membrane
  6. Lung
  7. Voice box
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40
Q
A
  1. Vesicles with mucus
  2. Goblet cell
  3. ER and Golgi
  4. Nucleus
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41
Q

What is the basement membrane?

A
  • sticky anchor for cells
  • holds cells in position
  • made of a protein carbohydrate matrix
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42
Q

What’s is golgis role in goblet cells?

A
  • exocytosis - transport protein out of cells
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43
Q

What is the ER role in goblet cell

A
  • protein synthesis
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44
Q

What are the adaptations of goblet cells?

A
  • large ER and Golgi apparatus
  • many vesicles from which mucus is secreted out of cell
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45
Q
  • Mucus traps ____________ ( dust, _________ ) and prevents them from entering alveoli
  • _____________ inhaled air
A
  • foreign particles
  • bacteria
  • moisturises
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46
Q

Epithelial cells line both the …….. and the …………

A

-outside (skin)
- inside of the body

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47
Q

Describe Psuedostratified epithelium structure

A
  • consists of a single layer of cells
  • nuclei are in different position giving the appearance of more than 1 year of cells ( therefore pseudostartified)
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48
Q

What type of epithelium lines trachea + bronchi

A

Pseudostratified columnar

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49
Q

What type of epithelia cells are in the bronchioles?

A
  • pseudostratified columnar
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50
Q

How does cystic fibrosis cause lung infections?

A
  • mucus traps bacteria but mucus is too sticky to be moved away by cilia
  • low oxygen levels in mucus so anaerobic bacteria thrive
  • WBC fighting bacteria dna and release DNA making mucus stickier
  • leading inflammation and infection
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51
Q

Why does cystic fibrosis cause breathing difficulties?

A
  • mucus blocks bronchioles so less/ no air
  • leading to reduced gas exchange
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52
Q

What is the Ficks law of diffusion

A

= rate of diffusion is inversely proportional to the thickness of the gas exchange surface

Rate of diffusion = ( surface area * difference in concentration ) / diffusion distance

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53
Q
A

1 - branch of pulmonary vein
2 - branch of pulmonary artery
3 - terminal bronchiole
4 - capillary
5 - alveoli

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54
Q
A

Terminal Bronchiole

1 - capillary from pulmonary vein
2 - blood plasma
3 - endothelium ( capillary wall )
4 - red blood cell
5 - surfactant and moisture
6 - capillary to pulmonary artery
7 - simple squamous epithelium ( alveolar wall )

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55
Q

What is surfactant and what is its role?

A

= phospholipid
- prevents permanent collapse and sticking together of alveoli

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56
Q

What makes gas exchange from alveoli to blood efficient

A
  • short diffusion distance
  • large concentration gradient
  • surface area
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57
Q

Short diffusion distance in the alveoli
- oxygen only diffuses through ____ cells (______________ and ______________ to reach the red blood cells)
- the _____________ epithelium of the alveoli is very ________
- capillaries have a very narrow _________ so distance to a RBC is short

A
  • two
  • epithelium
  • endothelium
  • squamos
  • thin
  • lumen
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58
Q
  • In the alveoli oxy conc is ___% ( due to the mixing of inhaled air with _______ air)
  • In the blood it is ____%
  • The 8% difference in oxygen levels between the alveoli and blood provides a ______________
A
  • 13
  • 5
  • large concentration gradient
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59
Q

How is surface area increased in the alveoli?

A
  • many alveoli which are very short
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60
Q

How does cystic fibrosis reduce surface area

A
  • mucus blocks bronchioles
  • fewer alveoli available for gas exchange
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61
Q

Mucus fills alveoli _________ diffusion distance

A
  • increasing
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62
Q

Why do people with cystic fibrosis have reduced elasticity in their lungs?

A
  • they over inflate their lungs to try and get enough oxygen
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63
Q

How does cystic fibrosis overall cause tiredness?

A
  • reduced gas exchange leading to an oxygen shortage
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64
Q

In the alveoli what type of epithelium cells are there?

A
  • simple squamous
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65
Q

What does Glycosylated mean?

A
  • A carbohydrate attached to an r group
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66
Q

What does phosphorylated mean?

A
  • phosphoryl group attached to the r group
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67
Q

Describe the experiment that show membrane was fluid

A
  • mouse cell and human cell membrane proteins were labelled with different dyes
  • the cells were fused together
  • after some time different proteins had mixed around in the membrane
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68
Q

What does the mouse cell + human cell membrane protein experiment show about membranes?

A
  • proteins (and lipids) in membranes move
  • membrane has fluid properties
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69
Q

Why is the fluid mosaic model described as fluid?

A
  • two dimensional ‘liquid’ with lateral movement of lipids and proteins through layer
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70
Q

Why is the fluid mosaic model described as mosaic?

A
  • composed of different types of macromolecules. For example integral/peripheral proteins, lipids and glycolipds.
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71
Q

What is the overall conclusion of lipids structure?

A
  • lipids form two dimensional liquid in which lipids can move
  • proteins attached to membrane
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72
Q
A

Lipid bilayer
1 - glycolipid
2 - channel protein
3 - integral protein
4 - integral transmembrane protein
5 - cholesterol
6 - peripheral protein
7- glycoprotein

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73
Q
A

Phospholipid
1 - Headgroup
2 - Phosphate
3 - Glycerol
4 - Fatty acid

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74
Q
A

Triglyceride
1 - glycerol
2 - fatty acid

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75
Q

What is the difference between triglycerides and phosopholipids

A

Phospholipid has only two fatty acids and replaces one with a phosphate

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76
Q
A

1 - head group
2 - phosphate
3 - glycerol
4 - saturated hydrocarbon fatty acid tails
5 - double bond ( gives bend )

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77
Q

Describe the nature of the head of the phospholipid

A

Hydropholic ( polar)

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78
Q

Describe the nature of the fatty acid tails

A
  • hydrophobic
  • non polar
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79
Q

Describe the arrangement of the phospholipid bilayer

A
  • Hydropillic heads face towards solution
  • Hydrophobic tails face away from solution
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80
Q

When a hydrocarbon is described as unsaturated it means that the hydrocarbon…

A

Contains double or triple bonds

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81
Q

If there are more unsaturated fatty acids phospholipids will be…

A
  • Less tightly packed
  • more movement possible
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82
Q

If there are more saturated fatty acids phospholipids will be…

A
  • tightly packed
  • less movement possible
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83
Q

If there is more cholesterol there is

A
  • reduced movement of phospholipids
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84
Q

Describe membrane permeability in terms of non polar molecules

A
  • non polar molecules can move through the membrane as they are not affected (repelled or attracted) by the hydrophilic heads
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85
Q

Describe membrane permeability in terms of polar molecules

A
  • polar molecules cannot move through the membrane due to the charged phospholipid head
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86
Q

Why can water travel through the membrane?

A
  • It is a very small and abundant molecule
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87
Q

Describe passive transport

A
  • not energy dependent:
  • diffusion
  • facilitated diffusion
  • osmosis
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88
Q

Describe active transport

A
  • energy dependent:
  • active transport
  • bulk transport
    - endocytosis
    - exocytosis
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89
Q

Describe diffusion

A
  • movement of molecules from an area where they are at high concentration to an area where they are at low concentration
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90
Q

Describe facilitated diffusion

A
  • movement of molecules from an area of high conc. to an area of low conc. via a carrier or channel protein
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91
Q

What is a gated channel

A
  • some channels can be opened by hormones or by a change in potential difference
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92
Q
A

1 - channel protein
2 - carrier protein
3 - polar molecules ( ions )
4 - larger molecules ( glucose )

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93
Q

describe osmosis

A

= movement of water molecules from a high water potential to a low water potential across a selectively permeable membrane

OR

= net movement of water into areas of high solute concentration across a selectively permeable membrane

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94
Q

How is movement of water molecules reduced by solute

A
  • water forms H-bonds with solute molecules
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95
Q

define hypotonic

A
  • solution with lower solute conc. than cell
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96
Q

What happens to animal cells if they are in a hypotonic solution

A

Lysed ( burst )

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97
Q

Define Isotonic

A
  • solution with the same solute concentration as cell
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98
Q

Define hypertonic

A
  • solution with higher solute conc than cell
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99
Q

What happens if an animal cell is in a hypertonic solution

A
  • shrivelled (crenate)
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100
Q

An animal cell is turgid in a __________ solution

A

Hypertonic

101
Q

An animal cell is flaccid in a ________ solution

A

Isotonic

102
Q

A plant cell is plasmolysed in a __________ solution

A

Hypertonic

103
Q

Describe Active transport

A
  • movement from a low concentration to a high concentration via carrier proteins using energy from ATP
104
Q

Define bulk transport

A

= energy dependent bulk transport out of and into cells

105
Q

Exocytosis is the export of molecules out of cells involving _____________ that _________ with the cell membrane and ________ their contents

A
  • vesicles
  • fuse
  • release
106
Q

Describe endocytosis

A
  • uptake of molecules by the creation of a vesicle from the cell membrane
  • cell membrane engulfs the molecules to be transported
107
Q

Phagocytosis is known as

A
  • cell eating ( solid particle )
108
Q

Placytosis is known as

A
  • cell drinking
  • extracellular fluid
109
Q

Receptor mediated is

A
  • specific form of endocytosis involving receptors and coat proteins
    Q
110
Q

What happens when there is too little water in the mucus of a healthy person ( non - CF )

A

1 - Cl ion are pumped into cell from tissue fluid across basal membrane against conc grad. Via ATP. They can’t go back through the basal membrane because they are polar
2 - CFTR channel is open causing Na+ channel to close. Cl- diffuses through the open CFTR channel
3 - Na+ diffuses down the electrochemical/ electrical gradient into the mucus ( where Cl- ions go Na+ will follow through the intercellular space/ tissue fluid)
4 - High salt conc. in the mucus draws water out of cells by osmosis - mucus becomes runny
5 - water is drawn into cells from tissue fluid by osmosis

111
Q

Why is mucus so sticky in cystic fibrosis

A

1 - CTFR is absent or non-function
2 - Na+ channel is permanently open and Na+ diffuses into cells from mucus and is pumped into tissue fluid
3 - Cl - diffuses out of mucus towards basal membrane via the intercellular space down an electrical gradient
4 -Water is continually removed from mucus by osmosis: mucus becomes sticky
5 - bacteria and wbc gets trapped; dna released from dead wbc makes mucus even more sticky

112
Q

How does CF affect digestion

A
  • mucus blocks pancreatic duct
  • macromolecules are not broken down
  • protease cannot leave and damages organ resulting in fibrosis and cysts
  • bile production/secretion is affected
  • fat soluble vitamins ( A D E K) not enough of
113
Q

Describe enzyme action

A
  • substrate binds to active site
  • enzyme substrates complex formed
  • enzyme catalyses reaction and products are formed
  • products no longer fit and are released
  • enzyme remains unchanged and it is free to be used again
114
Q

Active site

A
  • part of the folded protein where substrate binds
115
Q

Lock and Key theory

A
  • substrate shape is complementary to shape of active site
116
Q

Induced fit theory

A
  • substrate binding induces shape change in active site which enables perfect fit and catalytic activity
117
Q

How is activation energy lowered?

A
  • attraction between charged r group of active site and substrate was may distort shape of substrate and assists in formation of bond or breaking of bonds
  • ES complex restricts movement of substrate
118
Q

`What is a cofactor

A
  • non protein chemical compound that is bound to enzymes and required for enzyme action
119
Q

What is an apoenzyme

A
  • enzyme without its cofactor
120
Q

What is a holoenzyme

A
  • enzyme active because it has its cofactors
121
Q

Co enzyme

A
  • tightly bound cofactor
122
Q

Prosthetic group

A
  • loosely bound cofactor
123
Q

Competitive inhibitor

A

Competes with substrate for active site

124
Q

Non competitive inhibitor

A
  • binds to allosteric site and changes shape of active site
125
Q

The pyrimidines are single ring and include:

A
  • thymine
  • cytosine
126
Q

Purines are double rings and include:

A

-adenine
-guanine

127
Q

What is the first step in nucleotide formation?

A
  • deoxyribose + base -> nucleoside
  • condensation reaction
128
Q

What is step two of nucleotide formation

A

-phosphate + nucleoside -> nucleotide
-condensation reaction

129
Q

How are polynucleotides formed

A
  • a phosphate digester bond is formed between the deoxyribose of one nucleotide and the oh of a phosphate group on a different nucleotide
130
Q

What is the definition of transcription?

A
  • copying of a length of DNA code one gene long into messenger RNA (MRNA)
  • in the nucleus
  • catalysed by RNA polymerase
131
Q

Label these parts of DNA

A

1 - promoter (kicks starts transmission)
2 - gene
3 - terminator

132
Q

What are regulatory sequences?

A
  • promoter and terminator regions
133
Q

Describe step 1 of transcription

A

Transcription initiation
- RNA polymerase binds to DNA and stands for promoter regions
- RNA polymerase partially unwinds the DNA double helix
- RNA polymerase starts to transcribe DNA sequence on the anti-sense (template) strand into RNA sequence (via complementary base pairing)

134
Q

What is RNA synthesis?

A
  • anti-sense strand transcribed
    -> RNA has the same sequence as coding strand (U replaces T)
135
Q

RNA polymerase has ………… activity (unwinding of DNA ………………)

A
  • helicase
  • double helix
136
Q

What is polymerase activity?

A
  • formation of phosphodiester bonds
  • between RNA nucleotides in 5’ -> 3’ synthesis
137
Q

What is step 2 in transcription

A

Transcription elongation
-transcription continues until the terminator is reached

138
Q

What is step 3 in transcription

A

Transcription termination
-RNA polymerase reaches terminator
-transcription stops:
- RNA polymerase + transcript are released

139
Q

Describe RNA Processing

A

-RNA transcript is SPLICED = Introns are removed
-RNA transcript receives CAP AND TAIL
-process RNA transcript = MRNA

140
Q

What is rna export

A

-MRNA is exported out of the nucleus via pores in the nuclear membrane
1 - nucleus
2 - mrna

141
Q

What is wrong in CF in terms of digestive system?

A

-thick sticky mucus in the pancreatic duct and small intensive

142
Q

How is digestion affected by CF?

A

-digestive enzymes made in pancreas cannot reach the duodenum
-reduced absorption of food
-reduced absorption of nutrients (digestion products)

143
Q

The pancreas is damaged due to CF because…

A

Trapped digestive enzymes damage pancreatic tissue

144
Q

What is the result of trapped digestive enzymes damaging the pancreatic tissue?

A

-Islets of Langerhans get damaged
-insulin production reduced or stopped
-Type 1 Diabetes

145
Q

How does cystic fibrosis cause infertility?

A

-thick sticky mucus in reproductive system

146
Q

How does CF cause infertility in women?

A

-mucus blocks service
-pregnancy still possible but more likely with IVF (puberty delayed to age 15 on avg)

147
Q

How does cystic fibrosis cause infertility in men?

A

-50% have no sperm duct
-if sperm duct is present, it is usually blocked w/ mucus
-95% of sperm produced is abnormal
-only 1-2% of CF men can reproduce naturally (without IVF)

148
Q

How is sweat produced in healthy people?

A

-sweat is salty water made in sweat glands
-some salt is reabsorbed out of sweat duct into cells
(Cl- ions diffuse via CFTR, Na+ ions follow electrical gradient)

149
Q

How is sweat produced in CF patients?

A

-no functional CFTR so Cl- and Na+ are not reabsorbed and instead are lost in sweat)
-Sweat has much higher concentration of salt

150
Q

What is the definition of Translation?

A

= using the sequence of codons on mRNA to produce a sequence of amino acids in a protein

151
Q

Where does translation take place?

A

-in the cytoplasm on free ribosomes or on the rER

152
Q

What is translation catalysed by?

A

-ribosomes
-tRNA
-peptide synthetase

153
Q

What is the genetic code?

A

-Bases (= codon) code for 1 specific amino acid

154
Q

What is the definition of triplet code?

A

-3 bases code for 1 amino acid (AA)

155
Q

Degenerate is when some AAs…

A

Can be coded for by several codons

156
Q

What are the three stop codons?

A

-UAA
-UAG
-UGA

157
Q

What is the definition of universal?

A

-Same code in all organisms

158
Q

Each codons read separately because the codons are…

A

Non-overlapping

159
Q

Why is important that the genetic code is universal?

A

-due to common ancestry

160
Q

What are ribosomes?

A

=cell components responsible for protein synthesis

161
Q

What are ribosomes made up of?

A

-protein and ribosomal RNA (rRNA)

162
Q

Ribosomes contain small and…

A

Large subunits

163
Q

What type of ribosomes are there in prokaryotes (bacteria)?

A

70S

164
Q

What type of ribosomes are there in eukaryotes?

A

80S

165
Q

What does the S in 70/80S mean?

A

How long the ribosomes will take to settle

166
Q

The Svedberg unit (S) is a measure of ……………………. Time in a centrifuge.

A

Sedimentation

167
Q

Why do the ribosomes in eukaryotic cells have a higher Svedberg unit?

A

-They are larger and therefore take longer to settle at the bottom of a solution

168
Q

How do antibiotics work?

A

-They bind to the small subunit of bacterial ribosomes, stopping attachment of TRNA, therefore stopping protein synthesis

169
Q

Why do antibiotics kill bacteria but not other organisms?

A

Antibiotics bind much less successfully with the 80S ribosomes in eukaryotes, so have little effect on protein synthesis.

170
Q

TRNA has a ………………… shaped structure

A

Clover leaf

171
Q

tRNA has anticodon sequence which is…

A

Complementary to the codon

172
Q

tRNA binds to a ……………….. corresponding to anti-codon

A

Specific amino acid

173
Q

What are the two steps of translation?

A

-Translation initiation
-Translation elongation

174
Q

What happens in translation initiation?

A

-ribosome attaches to mRNA
-ribosome moves along mRNA (5’ -> 3’) to find first AUG (start codon)
-tRNA (carrying Met AA) with complementary anticodon pairs w/ codon through complementary base pairing

175
Q

What happens in translation elongation (1)?

A
  • next tRNA with anticodon complementary to next mRNA is loaded
    -adjacent AAs joined via a peptide bond (catalysed by peptide synthesise)
    -ribosome moves along mRNA and first tRNA is released
    -next tRNA with anticodon complementary to next mRNA codon is loaded
176
Q

What happens in translation elongation (2)

A

-adjacted AAS joined via a peptide bond (catalysed by peptide synthetase)
-ribosome moves along and second tRNA is released
-elongation continues until a stop codon is reached
-when the ribosome reaches a STOP codon a release factor is loaded and translation stops
-the ribosome and completed polypeptide are released from mRNA

177
Q

What are polysomes

A

-several ribosomes can bind to the same mRNA forming a polysome

-> several polypeptide chains are made simultaneously

178
Q

Proteins made on free ribosomes in the cytoplasm go to:

A

-cytoplasm
-nucleus
-mitochondria
-chloroplasts

179
Q

What is the rER

A

-rough endoplasmic reticulum

180
Q

Where do proteins on the rER go to?

A

-ER
-Golgi
-lysosomes
-plasma membrane
-secretory vesicles (exocytosis)

181
Q

What type of proteins fold the polypetide into secondary and tertiary structure?

A

-chaperones

182
Q

How many hydrogen bonds are between adenine and thymine?

A

2 hydrogen bonds

183
Q

How many hydrogen bonds are between guanine and cytosine?

A

3

184
Q

What is DNAs role?

A

-codes for amino acid sequence in proteins

185
Q

What is the sugar in DNA?

A

Deoxyribos

186
Q

What are the bases in DNA?

A

A C G T

187
Q

What is the structure of DNA

A

Double standard (ds) double helix

188
Q

IS DNA long or short?

A

Long

189
Q

Where is DNA located?

A

In the nucleus

190
Q

The amount of DNA is…

A

Constant in cells

191
Q

DNA is chemically very…

A

Stable

192
Q

What is RNAs role?

A

-component in mRNA and tRNA

193
Q

What is the sugar in RNA

A

Ribose

194
Q

What is the sugar in RNA

A

-ribose

195
Q

What are the bases in RNA

A

-ACGU

196
Q

What is the structure of RNA

A

-single stranded often secondary structure

197
Q

What is DNA replication?

A
  • copying of the entire genome in preparation for cell division
198
Q

what is step 1 of dna replication?

A
  • DNA helicase unwinds DNA double helix
199
Q

What is step 2 of DNA replication?

A
  • the two strands of the DNA double helix are separated by breaking hydrogen bonds between base pairs
200
Q

What is step 3 in dna replication?

A
  • parent strands act as template for new DNA strands
  • free nucleotides pair with their complementary nucleotides
  • dna polymerase forms phosphodiester bonds
201
Q

What is step 4 in dna replication?

A
  • two identical new strands of dna are made
202
Q

What’s is step 5 of dna replication?

A
  • newly formed DNA rewinds into helices
203
Q

What does semi-conservative mean?:

A
  • one strand of the original parental DNA
  • one new DNA strand
204
Q

DNA replication is semi…

A

Semi conservative

205
Q

What are the two alternative models of DNA replication?

A
  • conservative (1 old + 1 new DNA molecule)
  • dispersive / fragmentary (DNA molecules made randomly of 50% old and 50% new)
206
Q

What is the Meselson-stahl experiment?

A
  • one set of bacteria is grown with heavy 15N
  • another set of bacteria is grown with light 14N
  • isolation of DNA + centrifugal ion
    = DNA with heavy 15N at bottom
    = DNA with light 14N at top
207
Q

What type of DNA replication is this?

A

Semi-conservative

208
Q

What type of DNA replication is this?

A

Dispersive

209
Q

What type of DNA replication is this?

A

Conservative

210
Q

1 mistake made per ………….. nucleotides during replication

A

100,000

211
Q

What fixes 99% of mutations?

A
  • DNA polymerase proofreading
212
Q

What fixes mutations after DNA polymerase proofreading?

A
  • post-replication repair enzymes
213
Q

How many mutations are there per diploid cell per division?

A
  • 4
214
Q

What is a point mutation?

A
  • change in a single nucleotide (base)
215
Q

What happens if there a deletion mutation?

A

A nucleotide is missing
- frameshift mutation (reading frame changes - different AA sequence)

216
Q

What happens if there is an insertion mutation?

A

An additional nucleotide in the sequence
= frameshift mutation

217
Q

What happens if there is a substitution mutation?

A

A nucleotides is replaced by another
1. Silent mutation (degenerate code: no change in AA sequence)
2. Missense mutation (change in AA sequence)
3. Non-sense mutation (stop codon produces a truncated protein)

218
Q

What’s happens if there is an inversion mutation?

A

Nucleotides swapped
- missense mutation (change in AA sequence)

219
Q

What are the orgins of mutation?

A
  • mutagens (X-rays, UV light, chemicals) induce chemical changes in bases
220
Q

How many mutations are there for cystic fibrosis?

A
  • 1400
  • in 70% if cases its a F508 mutation
221
Q

What is a F508 mutation?

A
  • deletion of three nucleotides
  • missense mutation because the AA sequence changes
  • this causes a loss in the phenylanine amino acid which causes misfolding of the protein
222
Q

What is a chromosome?

A
  • a highly coiled linear strand of DNA and associated proteins (histones)
223
Q

What is a chromatid?

A
  • one of two strands of DNA that makes up a duplicated chromosome
224
Q

What is a centromere?

A
  • region where two sister chromatids attach
225
Q

What is a telomere?

A
  • protective region of repetitive nucleotide sequences at each end of a chromosome
226
Q

What are histones?

A
  • proteins that package and order the dna into chromosomes
227
Q

What is a homologous chromosome?

A
  • a pair of paternal and maternal chromosomes with same set of genes in same sequence
228
Q

What is a gene?

A
  • a region of DNA that codes for the amino acid sequence in a protein
229
Q

What is a gene locus?

A
  • specific location of a gene on a chromosome
230
Q

What is an allele?

A
  • a alternative form of a gene
231
Q

What does homozygous mean?

A
  • identical alleles on homologous chromsomes
232
Q

What does heterozygous mean?

A
  • different alleles on homologous chromosomes
233
Q

What does haploid mean?

A
  • one set of chromosomes (1n)
234
Q

What does diploid mean?

A
  • two sets of chromosomes (2n)
235
Q

What is genotype?

A
  • genetic make up/ alleles present
236
Q

What is phenotype?

A
  • visible characteristics caused by expression of alleles
237
Q

What is a dominant allele?

A
  • an allele that is always expressed in the phenotype
238
Q

What is a recessive allele?

A
  • an allele that is only expressed in the absence of a dominant allele/ when homozygous
239
Q

What is genetic testing?

A
  • dna is tested to see if it contains the most common mutations for a particular genetic disease
  • sample of cheek cell or WBC tested (in blood test)
240
Q

What is preimplantation genetic diagnosis? (PGD)

A
  • fertilisation by IVF
  • a cell is removed from the resulting embryos at the 8-16 stage
  • DNA is analysed
241
Q

Why is IVF required for PGD

A
  • several embryos needed
  • to be able to assess the embryos for testing
242
Q

What is amniocentesis?

A
  • during pregnancy 15-18 weeks
  • needle used to remove often l cells from amniotic fluid
  • DNA is analysed
243
Q

What are the advantedges of amniocentesis?

A
  • 1% chance of miscarriage
  • results after 3 days
244
Q

What are disadvantages of amniocentesis?

A
  • only carried out later in pregnancy
  • risk of false positives
245
Q

What is chronic villi sampling?

A
  • during pregnancy from 10 weeks
  • suction tube used to remove foetal cells from chorion
  • DNA is analysed
246
Q

What are the advantedges of CVS?

A
  • earlier in pregnancy
  • results available in 3 days
247
Q

What are disadvantages to do with CVS?

A
  • 1-2% of miscarrriage
  • risk of false positives
248
Q

What is newborn screening?

A
  • blood samples (heel prick test) at 5 days after birth
  • DNA is analysed

Biology (6 decks)

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