B1.2 What happens in cells Flashcards

1
Q

State the role of DNA in the body

A

DNA is the substance that contains all the instructions that determine your characteristics

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2
Q

Place in size order: gene, chromosome, genome, DNA, nucleus, cell, nucleotide

A

Nucleotide (smallest)

Gene

DNA

Chromosome

Genome

Nucleus

Cell (largest)

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3
Q

What is DNA?

A

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

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4
Q

Each long molecule (polymer) of DNA is a…

A

Chromosome

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5
Q

The units that make up the polymer DNA are called

A

nucleotides

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6
Q

Each nucleotides are composed of:

A

1 phosphate 1 deoxyribose 1 organic base

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7
Q

There are four organic bases

A

Adenine Thymine Cytosine Guanine

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8
Q

A gene is

A

A short section of DNA found upon a chromosome which codes for a specific protein

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9
Q

Name the protein that DNA coils around in the formation of a chromosome

A

Histone

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10
Q

What it complementary base pairing?

A

Adenine always pairs with thymine Cytosine always pairs with guanine

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11
Q

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

A

Double Helix

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12
Q

Why is the double helix described as being ‘anti-parallel’?

A

The two strands which form DNA are parallel but run in opposite directions

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13
Q

The phosphate and deoxyribose molecules in a DNA polymer are joined to form the…

A

sugar-phosphate backbone

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14
Q

What is the name of the weak bonds formed between bases of opposing strands of DNA?

A

Hydrogen bonds

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15
Q

Name the two main stages of protein synthesis

A

Transcription Translation

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16
Q

Where does protein synthesis take place

A

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

17
Q

Define transcription

A

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.

18
Q

Define translation.

A

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.

19
Q

What are the key differences between DNA and RNA?

A

DNA

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

RNA

RNA

  • Ribonucleotides
  • Bases: A, U, C, G
  • Sugar: ribose
  • Single strand
  • RNA can move in and out of the nucleus.
  • Short polynucleotide chain
  • Strands are continually made, broken down and reused
  • Synthesized from DNA on an as-needed basis.
20
Q

What are enzymes?

A

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

21
Q

What is the name of the molecule that an enzyme binds to?

A

Substrate

22
Q

What is an ‘active site’?

A

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.

23
Q

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

A

Lock and key hypothesis

24
Q

What is formed when a substrate binds to an enzyme

A

Enzyme-substrate complex

25
Q

State the factors affecting enzyme activity?

A
  • Temperature
  • pH
  • Substrate availability/concentration
  • Enzyme concentration
26
Q

What is the affect of temperature upon enzyme activity

A
  • The rate of reaction increases as increase kintetic energy, means increased number of successful collisions.
  • The higher the temperature, the faster the reaction
  • If the temperature becomes too high the enzyme denatures
27
Q

What does ‘denatured’ mean?

A
  • The structure of the protein that forms the enzyme has been altered due to high heat or a change in pH.
  • The change in shape affects the active site
  • The substrate can no longer bind with the enzyme
28
Q

If an enzyme is denatured, what happens to the rate of reaction?

A

As the enzyme can no longer catalyse the reaction, the rate of reaction decreases.

29
Q

How does substrate concentration affect enzyme-controlled reactions?

A

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