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1
Q

What does DNA stand for?

A

Deoxyribonucleic acid

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2
Q

How many chromosomes do humans have?

A

46

(23 from each parent)

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3
Q

Where is DNA?

A

DNA is in the nucleus of every one of our cells. Each long molecule of DNA is a chromosome.

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4
Q

What are short sections of DNA called?
(E.g that code for a characteristic, such as eye colour)

A

Genes

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5
Q

What do genes do?

A

The code that a gene contains causes specific proteins to be made. The particular proteins determine the cells function.

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6
Q

What is the structure of DNA?

A

DNA is made of two strands. These strands are joined together by bases. The strands are then twisted together. This forms a shape known as a double helix.

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7
Q

What is DNA made of?

A

DNA is made up of lots of small units called nucleotides, which are joined together. This means that DNA is a polymer.

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8
Q

About nucleotides

A

Each nucleotide is made of a sugar called deoxyribose, a phosphate group and a base =

Deoxyribose- phosphate- base

The two strands of DNA are held together by bonds between the bases

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9
Q

How many types of nucleotides are there in DNA

A

Four

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10
Q

What are the different bases of the nucleotides?

A

Adenine
Thymine
Cytosine
Guanine

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11
Q

What base in a nucleotide of DNA is characterised by the letter G?

A

Guanine

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12
Q

What base in a nucleotide of DNA is characterised by the letter A?

A

Adenine

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13
Q

What base in a nucleotide of DNA is characterised by the letter T?

A

Thymine

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14
Q

What base in a nucleotide of DNA is characterised by the letter C?

A

Cytosine

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15
Q

How do the bases in DNA bind?

A

To hold the strands of DNA together a base from one stand bonds with another base on the other strand. This forms a base pair. The base pairs always bond together in the same formation - this is called complementary base pairing.

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16
Q

What is complementary base pairing?

A

Two bases of nucleotides that bond together to hold the strands of DNA

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17
Q

What is the complementary base pair of adenine?

A

Adenine bonds with thymine
A-T

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18
Q

What is the complementary base pair of cytosine?

A

Cytosine always bonds with guanine
C-G

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19
Q

What is the complementary base pair of thymine?

A

Thymine always bonds with adenine
T-A

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20
Q

What is the complementary base pair of guanine?

A

Guanine always bonds with cytosine
G-C

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21
Q

What is mRNA?

A

mRNA (messenger RNA) is like a single strand of DNA

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22
Q

How is mRNA produced

A

Through transcription

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23
Q

What is transcription?

A

-The DNA around a gene unzips so both strands are separated
-one of the DNA strands act as a template
-Complementary bases attach to the strand being copied
-for example cytosine (C) joins to guanine(G)
-this forms a strand of mRNA
-there is no thymine(T) in mRNA so a base called uracil (U) bonds with adenine
-once complete the, strand of mRNA detaches from the DNA template and the DNA zips back up
-mRNA is small enough to fit outside of the nucleus. It travels to sub cellular structures called ribosomes in the cytoplasm. This is where the protein will be made

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24
Q

What is Uracil?

A

Uracil (U) is a base that bonds with adenine (A) during the creation of mRNA via transcription

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25
What are proteins made from?
A protein is made from amino acids, different amino acids join together to form different proteins.
26
What determines which amino and proteins are made?
The order of nucleotides in your DNA determines the type and the order of amino acids, and this determines which proteins are produced
27
How are proteins made?
Proteins are made via a process called translation. The mRNA attaches to a ribosome. Here the nucleotide sequence is interpreted and the new protein is made:
28
How does translation work?
-the ribosome “reads” the nucleotides on the mRNA in groups of three -these groups are called base triplets (or codons)Each triplet code for a specific amino acid. For example, CGU codes for a different amino acid to ACG -the ribosome continues to “read” the triplet code,adding more and more amino acids -The amino acids join together in a chain.This is a protein
29
What determines how the protein will fold?
The sequence of amino acids determines how the protein will fold. Each type of protein has a specific shape. This is important for protein function. Many types of proteins are produced including enzymes and hormones.
30
What are enzymes?
-Enzymes are made of protein -they are biological catalysts -this means they speed up a reaction without being used up themselves -once a reaction is finished they can be used to speed up the same type of reaction again
31
What reactions in our bodies are enzymes involved in?
-Building larger molecules from small ones, such as in protein synthesis -break down large molecules into smaller ones, such as in digestion
32
What do enzymes look like?
Enzymes,like all proteins are made up of long chains of amino acids. These are folded together to form a specific shape. The shape of one part of the enzyme is particularly important Here, molecules of other substances bind to the enzyme. This is called the active site
33
What is the molecule that binds to the enzyme called?
The substrate
34
Do enzymes bind to all molecules?
No, enzymes are highly specific. This means they can only bind to one type of substrate molecule The substrate must fit exactly into the active site. If it does not, the molecule cannot bind.
35
What is the term given to the process of molecules or substrate binding to an active site of an enzyme.
Lock and key hypothesis
36
What factors affect enzymes?
The rate of an enzyme-catalysed reaction depends on a number of factors such as: Temperature Ph
37
How does temperature affect enzymes
At higher temperatures the enzyme and substrate molecules move faster and collide more often.
38
What happens if the temperature is too high?
The amino acid chains in the protein start to unravel, changing the shape of the active site. The enzyme is now denatured.
39
What happens when an enzyme becomes denatured?
The substrate can no longer bind and so the rate of reaction decreases. Once all enzymes are denatured, the reaction stops. Most denatured enzymes cannot return to their original shape - the change is irreversible.
40
How does PH affect enzyme-controlled reactions?
Each enzyme has its optimum pH. A change in pH affects the interactions between amino acids in a chain. This may make the enzyme unfold.
41
How does enzyme and substrate concentration affect the rate of reaction
They have a maximum which is reached when either all of the substrate is used up or there are no more enzymes left to bind to.
42
What suffix do sugar molecules usually have at the end of their name?
Ose (e.g glucose,sucrose)
43
What suffix do enzymes usually have at the end of their name?
Ase (e.g lipase, amylase, protease)
44
What is the chemical reaction for aerobic respiration?
C6H12 + 6O2 ——> 6CO2 + 6H2O
45
What are the three main uses for ATP
-to synthesis larger molecules from smaller ones -for movement -animals use ATP to contact muscle cells enabling movement -to stay warm- animals increase the rate of respiration when their surroundings are colder than they are this transfers more energy so they remain at a constant temperature
46
Where does respiration to place inside a cell?
Mitochondria
47
What type of reaction is respiration?
Exothermic
48
Anaerobic respiration
The body transfers energy from its chemical store in glucose
49
What is the word equation for anaerobic respiration?
Glucose —> lactic acid
50
What factors affect the rate of diffusion?
-Decreasing the distance needed -increasing the concentration gradient -Increase the surface area
51
Where does ATP come from?
Respiration
52
What are the key features of active transport?
-Particles are transported (pumped) against a concentration gradient (low concentration to high) -ATP is required -The process makes use of carrier proteins in the cell membrane
53
What are carrier proteins?
-Special proteins that span accords the width of the cell membrane
54
What do carrier proteins do?
-A particular molecule that the cell requires bonds to a specific carrier protein -Energy is transferred from an energy store (ATP) to the protein so that it can change shape or rotate. The carrier protein transports the molecule into the cell.
55
What is mitosis?
The process by which body cells divide to produce two genetically identical cells
56
What’s re the uses of mitosis?
-repair damaged tissue -replace dead cells -growth
57
What is DNA replication?
DNA is replicated
58
What happens in DNA replication?
-DNA unzips (hydrogen bonds break - by specific enzymes) -Free floating nucleotides pair up to the exposed bases via complementary base pairing to form base pairs -continues until two identical DNA molecules are made
59
What is the order of DNA replication?
Cell growth —> DNA synthesis (46 becomes 92) —>cell growth —> mitosis —> cytokinesis
60
What is cytokinesis?
The splitting of cytoplasm and cell membrane 2x 46
61
What is G1, S and G2?
Interphase
62
What is the order of events during DNA replication?
G1 —> S —> G2 —> mitosis —> cytokinesis
63
What happens during G1?
Cell growth
64
What happens during S?
Synthesis
65
What happens during G2?
Cell growth
66
Is DNA replication and transcription the same?
NO
67
What are the stages of mitosis in order?
1.Prophase 2.Metaphase 3.Anaphase 4.Telophase
68
What comes after mitosis?
Cytokinesis
69
What happens during prophase
1.chromosomes are visible as chromatids (x shape) joined by a centromere , nuclear membrane breaks down
70
What happens during metaphase?
2.chromatids line up across the equator/centre of the cell. Cell(spindle) fibres form
71
What happens during anaphase?
3.one set of the identical chromosomes(chromatids) are pulled to opposite poles of the cell by fibres
72
What happens during telophase?
4.The cytoplasm and cell membrane divide to produce two genetically identical cells (cytokinesis)
73
What does differentiation do?
-ensures efficiency in multicellular organisms -cells express specific genes —> produce proteins characteristics for cell
74
How are red blood cells fit for their purpose?
-Small+flexible to pass through capillaries -No nucleus so there can be more haemoglobin -Lots of haemoglobin so more oxygen and quicker respiration -Biconcave disk —> larger surface area: volume ratio so quicker rate of diffusion for o2 and Co2 -thin membrane so shorter diffusion distance and thus more diffusion
75
How is a root hair cell fit for its purpose?
-Large vacuole to store water ions and sugar -can take minerals in to survive -long + thin so can penetrate some particles -large surface area so faster rate of uptake -Lots of mitochondria to produce ATP via aerobic respiration
76
What are embryonic cells?
Cells which can differentiate into all cell types (pluripotent)
77
What adult stem cells?
Cells which can differentiate into some cell types (multi potent)
78
Why are embryonic stem cells good?
-ESC’s are easy to get -ESC’s can make any specialised cell -can save lives/treat illnesses
79
Why are embryonic stem cells bad?
-Limited number of ESCs -ESCs are potential life -There is a risk if rejection -Taking cells gives a higher risk of infection/cancer
80
Why are adult stem cells good?
-Unlimited number of ASCs -Can save lives/treat illnesses
81
Why are adult stem cells bad?
-ASCs are hard to obtain -ASCs can only make specific cells -There is a risk of rejection -Taking ASCs is tiring/uncomfortable -Taking cells gives a higher risk of cancer
82
Uses of adult stem cells in medicine
-could be used to cure diseases e.g diabetes ,paralysis -can be used to repair/ replace damaged organ tissues
83
What can plant cells do?
-differentiate into any cell type -retain the ability to differentiate into any type of cell throughout life It is found in the meristem
84
How do you get SA:V ratio?
Surface area/ volume = n:1
85
What happens to an eye when looking at a near object?
-Ciliary muscles contract -Suspensory ligaments slack -Lens is thick
86
What happens to an eye when looking at a far away object?
-ciliary muscles relax -suspensory ligaments become tense -the lens is thin
87
How do you correct short sightedness?
A concave lens as it bends light before it enters the eye
88
How do you correct long sightedness?
A convex lens as light bends inwards before it enters the eye
89
What is the circulatory system?
A network of blood vessels (arteries,capillaries,veins), heart and lungs
90
What does the circulatory system do?
Transports substances the body needs (e.g oxygen, glucose)
91
Closed system
Blood remains in these structures
92
What kind of circulatory system do fishes have?
Single circulatory systems are found in fish
93
How does a single circulatory system in a fish work?
Blood pumped by the heart to the gills for oxygenation Lower blood pressure
94
How does a double circulatory system work?
-maintains a high pressure -faster flow to supply more oxygen to cells -helps to maintain core body temperature
95
What do ribosomes do?
mRNA will attach to a ribosome in the cytoplasm and the ribosome will read the mRNA bases in groups of 3(codon)0
96
What does a codon code for?
1 amino acid
97
What will the ribosomes do after reading the codon?
Produce tRNA which will bring a specific amino acid from the cytoplasm to the ribosome where the tRNA will bond with the mRNA
98
In what process does mRNA attach to a ribosome? (Translation it transcription)
Translation
99
What is thymine replaced by the n transcription?
Uracil replaces thymine so A-U instead of A-T

Biology (11 decks)

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