B1.2 What happens in cells

Question 1

<p>State the role of DNA in the body</p>

Answer 1

<p>DNA is the substance that contains all the instructions that determine your characteristics</p>

Question 2

<p>Place in size order: gene, chromosome, genome, DNA, nucleus, cell, nucleotide</p>

Answer 2

<p>Nucleotide (smallest)</p>

<p>Gene</p>

<p>DNA</p>

<p>Chromosome</p>

<p>Genome</p>

<p>Nucleus</p>

<p>Cell (largest)</p>

Question 3

<p>What is DNA?</p>

Answer 3

<p>DNA is deoxyribose nucleic acid, the genetic material found within the nucleus of every one of your cells.</p>

Question 4

<p>Each long molecule (polymer) of DNA is a...</p>

Answer 4

<p>Chromosome</p>

Question 5

<p>The units that make up the polymer DNA are called</p>

Answer 5

<p>nucleotides</p>

Question 6

<p>Each nucleotides are composed of:</p>

Answer 6

<p>1 phosphate1 deoxyribose1 organic base</p>

Question 7

<p>There are four organic bases</p>

Answer 7

<p>AdenineThymineCytosineGuanine</p>

Question 8

<p>A gene is</p>

Answer 8

<p>A short section of DNA found upon a chromosome which codes for a specific protein</p>

Question 9

<p>Name the protein that DNA coils around in the formation of a chromosome</p>

Answer 9

<p>Histone</p>

Question 10

<p>What it complementary base pairing?</p>

Answer 10

<p>Adenine always pairs with thymineCytosine always pairs with guanine</p>

Question 11

<p>What is the name of the structure formed by DNA, as discovered by Watson and Crick in the 1950s</p>

Answer 11

<p>Double Helix</p>

Question 12

<p>Who produced the first ever photograph of DNA, ‘photo 51’, that led to the discover of DNA's structure.</p>

Answer 12

<p>Rosalind Franklin</p>

Question 13

<p>Why is the double helix described as being 'anti-parallel'?</p>

Answer 13

<p>The two strands which form DNA are parallel but run in opposite directions</p>

Question 14

<p>The phosphate and deoxyribose molecules in a DNA polymer are joined to form the...</p>

Answer 14

<p>sugar-phosphate backbone</p>

Question 15

<p>What is the name of the weak bonds formed between bases of opposing strands of DNA?</p>

Answer 15

<p>Hydrogen bonds</p>

Question 16

<p>Name the two main stages of protein synthesis</p>

Answer 16

<p>TranscriptionTranslation</p>

Question 17

<p>Where does protein synthesis take place</p>

Answer 17

<p>Transcription - starts in the nucleus, and ends when the mRNA strand leaves through the nuclear pore to towards the ribosomes Translation - In the cytoplasm with the assistance of ribosomes</p>

Question 18

<p>Define transcription</p>

Answer 18

<p>The process by which DNA unzips to allow mRNA to use it as a template to make a copy of a section which codes for a specific protein. Once copied the mRNA detaches and leaves the nucleus and the DNA zips back up.</p>

Question 19

<p>Define translation.</p>

Answer 19

<p>The process by which mRNA is read by the nucleus in groups of three 'codons', to produce a protein. During translation tRNA molecules are attracted to their complementary bases upon the mRNA bringing specific amino acids with them that join together into a chain to form a protein.</p>

Question 20

<p>What are the key differences between DNA and RNA?</p>

Answer 20

<p><strong>DNA</strong></p>

<ul> <li>Deoxyribonucleotides</li> <li>Bases: A, T, C, G</li> <li>Sugar: deoxyribose</li> <li>Double helix</li> <li>Can not leave the nucleus</li> <li>Long polynucleotide chain</li> <li>DNA is completely protected by the body from degradation.</li> <li>Self-replicating</li></ul>

<p></p>

<p><strong>RNA</strong></p>

<p>RNA</p>

<ul> <li>Ribonucleotides</li> <li>Bases: A, U, C, G</li> <li>Sugar: ribose</li> <li>Single strand</li> <li>RNA can move in and out of the nucleus.</li> <li>Short polynucleotide chain</li> <li>Strands are continually made, broken down and reused</li> <li>Synthesized from DNA on an as-needed basis.</li></ul>

Question 21

<p>What are enzymes?</p>

Answer 21

<p>Proteins which act as biological catalysts - meaning they speed up reactions without being used up in the process.</p>

Question 22

<p>What is the name of the molecule that an enzyme binds to?</p>

Answer 22

<p>Substrate</p>

Question 23

<p>What is an 'active site'?</p>

Answer 23

<p>An active site is part of an enzyme that binds to the substrate.It has a specific shape which is formed by the way its amino acids are folded togther within the protein.</p>

Question 24

<p>This hypothesis states that only one substrate will fit one enzyme, and that they must be an exact fit.</p>

Answer 24

<p>Lock and key hypothesis</p>

Question 25

<p>What is formed when a substrate binds to an enzyme</p>

Answer 25

<p>Enzyme-substrate complex</p>

Question 26

<p>State the factors affecting enzyme activity?</p>

Answer 26

<ul> <li>Temperature</li> <li>pH</li> <li>Substrate availability/concentration</li> <li>Enzyme concentration</li></ul>

Question 27

<p>What is the affect of temperature upon enzyme activity</p>

Answer 27

<ul> <li>The rate of reaction increases as increase kintetic energy, means increased number of successful collisions.</li> <li>The higher the temperature, the faster the reaction</li> <li>If the temperature becomes too high the enzyme denatures</li></ul>

Question 28

<p>What does 'denatured' mean?</p>

Answer 28

<ul> <li>The structure of the protein that forms the enzyme has been altered due to high heat or a change in pH.</li> <li>The change in shape affects the active site</li> <li>The substrate can no longer bind with the enzyme</li></ul>

Question 29

<p>If an enzyme is denatured, what happens to the rate of reaction?</p>

Answer 29

<p>As the enzyme can no longer catalyse the reaction, the rate of reaction decreases.</p>

Question 30

<p>How does substrate concentration affect enzyme-controlled reactions?</p>

Answer 30

<p>The higher the substrate availability the higher the rate of reaction until all the enzyme-substrate bases are used up.</p>