Level 2 Bio: Gene Expression Flashcards

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1
Q

Anticodon

A

Three consecutive bases on the tRNA

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2
Q

Codon

A

Three consecutive bases on the mRNA

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3
Q

Deletion mutation

A

A mutation on the DNA where a base(s) is removed, resulting in a frame shift

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4
Q

DNA

A

Deoxyribose nucleic acid, A joins with T, C joins with G. Double stranded, helix shaped large molecule, a whole chromosome. Deoxyribose sugar

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5
Q

Enzyme

A

A folded protein which acts as a biological catalyst to speed up the rate of a chemical reaction in an organism

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6
Q

Frameshift

A

Change in bases that the ribosome reads

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7
Q

Gene

A

A piece of DNA which codes for the making of a protein/feature

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8
Q

Gene expression

A

The process where the instructions on our DNA are converted into a functional protein, includes transcription, translation and protein folding

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9
Q

Genotype

A

The genetic makeup of an organism for a feature

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10
Q

Insertion mutation

A

A mutation on the DNA where a base(s) is added resulting in a frame shift

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11
Q

Metabolic pathway

A

A series of enzyme controlled reactions, where the product of one reaction becomes the substrate of the next

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12
Q

Missense mutation

A

A change of the base on the DNA which codes for a different amino acid. This may or may not alter the shape of the protein and therefore its function.

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13
Q

mRNA

A

Messenger RNA. Made during transcription in the nucleus. Carries the instructions of the ribosome to make a polypeptide chain. Contains codons.

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14
Q

Mutagen

A

Environmental factor which causes the mutation e.g x-rays etc

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15
Q

Mutation

A

A sudden permanent change in the DNA base sequence

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16
Q

Non-sense mutation

A

A change of the base on the DNA which changes the instructions so a STOP codon occurs in the wrong place. Protein is greatly affected.

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17
Q

Peptide bond

A

Bond formed between 2 amino acids during translation

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18
Q

Phenotype

A

The physical appearance of a feature.

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19
Q

Point mutation

A

A change of only one or a few bases on the DNA

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20
Q

Protein

A

A substance made up of many amino acids joined together to form a polypeptide chain, which gets folded into a functional protein (enzymes area type of protein)

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21
Q

Redundancy

A

The fact that multiple codons code for the same amino acid, eg CCU, CCC, CCA and CCG all code for the amino acid Pro

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22
Q

Same-sense mutation

A

A change of the base on the DNA where the bases still code for the same amino acid. This is due to the redundancy of the genetic code.

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23
Q

Silent mutation

A

A mutation that is neither favourable nor harmful, that remains in a population.

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24
Q

Start codon

A

The start signals on the mRNA which initiates translation. Always AUG.

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25
Q

Stop codon

A

These 3 codons on the mRNA (UAA, UAG, UGA) do not code for an amino acid therefore telling the ribosome where to stop translation.

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26
Q

Substitution mutation

A

A mutation where the base(s) on the DNA are swapped

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27
Q

Transcription

A

The process by which DNA going to mRNA, occurs in the nucleus. Controlled by RNA polymerase

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28
Q

Translation

A

The process by which mRNA going to polypeptide chain, occurs in the cytoplasm on the ribosome

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29
Q

Triplet

A

Three consecutive bases on the DNA

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30
Q

tRNA

A

Transfer RNA. Carries an amino acid to the ribosome. 3 bases on the mRNA= an anticodon

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31
Q

What is gene expression

A

Gene expression is the process by which information from a gene is used to make a protein.

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32
Q

What does the base sequence of a DNA molecule code for

A

The base sequence of a DNA molecule codes for the amino acids that make up proteins.

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33
Q

What codes for 1 amino acid

A

A sequence of 3 bases in DNA (a triplet) codes for 1 amino acid

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34
Q

A sequence of many amino acids joined together with peptide bonds forms a __________

A

A sequence of many amino acids joined together with peptide bonds forms a POLYPEPTIDE.

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35
Q

One gene codes for one _________ (basic protein, most proteins made of many Polypeptides).

A

One gene codes for one POLYPEPTIDE (basic protein, most proteins made of many Polypeptide).

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36
Q

What is the primary structure

A

The primary structure is the simplest type of protein structure. It is the linear chain of amino acids that make up a protein.

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37
Q

The primary shape is bent or twisted into a helix or pleated sheet. The shape is held in place by _________ bonds. The secondary structure is the folded structures that forms within a polypeptide when atoms interact on the “backbone”.

A

The primary shape is bent or twisted into a helix or pleated sheet. The shape is held in place by HYDROGEN bonds. The secondary structure is the folded structures that forms within a polypeptide when atoms interact on the “backbone”.

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38
Q

In the alpha helix the carbonyl of one amino acid is hydrogen bonded to the amino H of an amino acid 4 down the chain. This bonding pattern pulls the polypeptide chain into a ________ structure resembling a curled ribbon.

A

In the alpha helix the carbonyl of one amino acid is hydrogen bonded to the amino H of an amino acid 4 down the chain. This bonding pattern pulls the polypeptide chain into a HELICAL structure resembling a curled ribbon.

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39
Q

The tertiary structure is the folding of what?

A

The tertiary structure is the folding of secondary structures bent into a globular shape & is the 3D structure of the protein.

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40
Q

Quaternary structures are made of 2 or more ____________ chains held loosely together.

A

Quaternary structures are made of 2 or more POLYPEPTIDE chains held loosely together.

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41
Q

Globular proteins have what kind of a function

A

Globular proteins have a chemical function

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42
Q

Fibrous protein molecules form long chains or fibres (they have primary, __________, tertiary and __________ structure). Their fibrous nature makes them __________ in water

A

Fibrous protein molecules form long chains or fibres (they have primary, SECONDARY, tertiary and QUATERNARY structure). Their fibrous nature makes them INSOLUBLE in water

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43
Q

mRNA=??

A

Messenger RNA

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44
Q

rRNA=??

A

Ribosomal RNA

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45
Q

tRNA=??

A

Transfer RNA

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46
Q

DNA codes for_________

A

Proteins

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47
Q

Where are proteins synthesised

A

In ribosomes

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48
Q

RNA stands for

A

Ribonucleic acid

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49
Q

DNA stands for

A

Deoxyribonucleic acid

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50
Q

Nucleic acids (make up DNA) are ________ composed of monomers (smaller units) called a ________

A

Nucleic acids (make up DNA) are POLYMERS composed of monomers (smaller units) called a NUCLEOTIDE

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51
Q

What is the monomer of DNA

A

Nucleotide: sugar, base & phosphate

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52
Q

The bases in DNA are=??

A

Cytosine with Guanine & Thymine with Adenine

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53
Q

The bases in RNA are=??

A

Cytosine with Guanine & Uracil with Adenine

54
Q

The length of RNA is much _________ than DNA

A

The length of RNA is much SHORTER than DNA

55
Q

What are the 3 different types of RNA

A

1) messenger RNA: mRNA
2) Transfer RNA: tRNA
3) Ribosomal RNA: rRNA

56
Q

What does mRNA do

A

copies a gene on DNA & transfers this genetic information to a ribosome & acts as a template

57
Q

What does tRNA do

A

picks up specific amino acids & takes them to the ribosome to assemble into proteins.

58
Q

What does rRNA do

A

clicks the amino acids together into proteins & folds them into three dimensional shapes

59
Q

What are the similarities between DNA & RNA

A

Both have nucleotides, Both found in all cells, They both have 4 bases

60
Q

How is DNA different to RNA in terms of structure

A

It is double stranded & longer, more stable

61
Q

How is RNA different to DNA in terms of structure

A

It is single stranded & shorter, less stable

62
Q

How is DNA different to RNA in terms of location

A

Only in nucleus

63
Q

How is RNA different to DNA in terms of location

A

In and out of nucleus

64
Q

How is DNA different to RNA in terms of bases/base pairing

A

Has Adenine, Guanine, Cytosine & Thymine. A to T, C to G

65
Q

How is RNA different to DNA in terms of bases/base pairing

A

Has Adenine, Guanine, Cytosine & Uracil. A to U, C to G

66
Q

How is DNA different to RNA in terms of sugars

A

Deoxyribose sugar

67
Q

How is RNA different to DNA in terms of sugars

A

Ribose sugar

68
Q

What are the main reasons for the significant differences between DNA and RNA

A

DNA has to be really big because it contains all of the genetic material for the organism. It is a double helix to allow it to be more stable. Because it is such a big molecule it can’t leave the nucleus. RNA has to be small so that it can leave the nucleus.

69
Q

Summary of what mRNA does

A

carries a copy of the gene

70
Q

Summary of what rRNA does

A

forms the structure of a ribosome (the site where proteins are made)

71
Q

Summary of what tRNA does

A

transfers amino acids to the ribosome.

72
Q

Describe the role of mRNA

A

Copies the gene from the DNA, carries the copy out of the nucleus to the ribosome.

73
Q

Describe the role of rRNA

A

forms the structure of the ribosome, enables amino acids to form peptide bonds, making a polypeptide chain.

74
Q

Describe the role of tRNA

A

picks up a specific amino acid and TRANSFERS it to the ribosome.

75
Q

What are the monomers of proteins

A

amino acids

76
Q

What is a purine

A

A purine is a double ringed molecule

77
Q

What is a pyrimidine

A

A single ringed molecule

78
Q

Name the 2 functional groups found in all amino acids

A

1) Amino group
2) Carboxylic group

79
Q

Primary structure

A

Peptide bonds link amino acid within proteins. The sequence of amino acids is known as the primary structure of a protein. The peptide bonds, along with the a-carbon atoms wo which r-groups are attached, form the protein backbone.

80
Q

Secondary structure

A

Segments of polypeptides often fold locally into stable structures that include helices and sheets. In a helix (alpha helix), the polypeptide backbone follows a helical path. The helical shape is held in place by hydrogen bonds. In a sheet (beta sheets), strands of protein lie adjacent to one another and are held in place by hydrogen bonds between the peptide backbones.

81
Q

Tertiary structure

A

Tertiary protein structure refers to the compete 3D folding of a protein and gives the protein a specific shape. It is held in place by salt ridges, hydrogen bonds and disulphide bonds.

82
Q

Quaternary structure

A

Quaternary structures contain two or more tertiary units. For example, haemoglobin consists of two alpha chains and two beta chains. Collagen consists of three helices.

83
Q

Name the type of bonding that occurs between amino acids within the primary structure of proteins

A

peptide bonds

84
Q

name the type of bonding that maintains the secondary structure of proteins

A

Hydrogen bonds

85
Q

Name the 2 types of secondary protein structure

A

alpha helix and beta sheets

86
Q

Describe the main differences between the Primary and secondary structure of proteins

A

the primary structures is the sequence of amino acids within the protein. Secondary structure is how the protein folds with the hydrogen bonds found between peptide backbones.

87
Q

Describe the main differences between the tertiary and quaternary structure of proteins

A

tertiary structure is the 3D folding of a protein and gives it a specific shape. Quaternary structure is 2 or more tertiary units.

88
Q

What is a fibrous protein

A

Fibrous proteins form long protein filaments, that are shaped like rods. They are usually inert, insoluble in water and very tough. Fibrous proteins are typically used for structural support and movement (e.g skin, collagen)

89
Q

What is a globular protein

A

Globular proteins are polypeptide chains folded into large, round molecules. They are soluble in water and therefore easily transported through the body. However, they are relatively unstable and susceptible to slight changes in temperature and pH . These globular proteins typically have a chemical function such catalysing reactions, transporting chemicals, regulation and protection

90
Q

What are the 2 key things to do with reading protein synthesis

A

“read up” 3’ to 5’

“Write down” 5’ to 3’

91
Q

What does RNA polymerase form

A

RNA polymerase forms mRNA, RNA nucleotides COMPLEMENTARY base pair with the template strand of DNA.

92
Q

What are the 2 parts of protein synthesis

A

1) Transcription
2) Translation

93
Q

What happens in transcription

A

First a copy of a gene on the template strand of the DNA is made by mRNA. This moves out from the nucleus through the nuclear pore into the cytoplasm to a ribosome.
The ribosome then connects the large and small sub unit around the mRNA.
The copy of each triplet in the DNA which is on the mRNA is now called a codon.

94
Q

What happens in translation

A

The ribosome moves along the MRNA reading the series of codons (3 bases on the mRNA). Each of these codons code for a specific amino acid.

95
Q

What is a summary of protein synthesis in 8 steps

A

1) DNA unwinds
2) RNA polymerase brings nucleotides to complementary base pair
3) DNA coils up again using base pairing rules
4) The copied mRNA leaves the nucleus through the nuclear pores.
5) tRNA with the anticodon comes in to bind to the codon on the mRNA.
6) Anticodon binds to the triplet making part of a polypeptide chain.
7) The tRNA leaves to make space for the next one
8) Amino acid bonds to tRNA with the correct anticodon

96
Q

What are the 10 structures involved in protein synthesis

A

1) DNA
2) Nucleotides
3) Enzyme Polymerase
4) DNA template strand
5) Nuclear membrane
6) Nuclear pore
7) tRNA molecule
8) Amino acids
9) Ribosome
10) Polypeptide chain

97
Q

How many different amino acids & nucleotides are there

A

There are 20 different amino acids and only 4 different nucleotides

98
Q

With 20 different amino acids and 4 different nucleotides how many possible combinations are there

A

64

99
Q

What are some amino acids coded for by…..

A

Some amino acids are coded for by more than one codon e.g Serine is made form one of six codons. This is called REDUNDANCY. This is a back up in case a mutation occurs.

100
Q

Why are the first 2 bases critical

A

The first 2 bases are critical in determining which amino acid is coded for. The third base can be anything. This is called DEGENERACY. If a mutation happens to affect the 3rd base, the correct amino acid will still be made and used.

101
Q

What is the purpose of Transcription

A

This is when the code (for making a specific protein) on DNA is written across “transcribed” onto the mRNA molecule so that the “code” to build the protein can get to the ribosome.

102
Q

What is the purpose of Translation

A

This is when the copied (transcribed) code sequence carried on the mRNA out to the ribosome is ‘translated’ and used to create a polypeptide chain and functional protein.

103
Q

What is the 1st step of Transcription

A

RNA Polymerase unwinds/separates the DNA double helix - along the GENE TO BE COPIED, forming a ‘transcription bubble” - the nucleotide bases get exposed

104
Q

What is the 2nd step of Transcription

A

One strand of the DNA is used as a TEMPLATE strand (pattern) to make mRNA by using the complimentary base pair sequence A-U and G-C. The other strand remains as the PARENT/CODING/sense strand.

105
Q

What is the 3rd step of Transcription

A

RNA Polymerase binds to the DNA Template strand at (a special sequence of nucleotides) called the PROMOTER (this also identifies the Template Strand)

106
Q

What is the 4th step of Transcription

A

RNA Polymerase builds the mRNA - attaches free nucleotide bases complimentary (to the template strand) A-U and G-C . (so that the mRNA molecule is complimentary to the DNA template)

107
Q

What is the 5th step of Transcription

A

The enzyme RNA Polymerase is the enzyme that copies the “specific code” for each specific protein onto newly built mRNA

108
Q

What is the 6th step of Transcription

A

Once RNA Polymerase reads the TERMINATOR CODON - Transcription is complete for that specific protein code - the mRNA detaches - non coding regions of DNA called introns are removed to create a “mature” RNA molecule ready to leave the nucleus (via the nuclear pores) to go to the Ribosome

109
Q

What is the 7th step of Transcription

A

After completion of the mature RNA the two DNA strands rejoin (anneal) by reformation of the H bonds. Ready for the next protein to be made and for the process to repeat.

110
Q

What is the 1st step of Translation

A

A start codon initiates the start of translation - this is always codes for the amino acid Methionine and is AUG

111
Q

What is the 2nd step of Translation

A

mRNA arrives at the ribosome and forms a ‘complex” with it - by binding to it. (ribosomes are usually close to the nucleus)

112
Q

What is the 3rd step of Translation

A

The ribosome is an organelle which “reads” mRNA bases in a code of 3 bases at at time. (normally several ribosomes move along the mRNA at any one time ensuring rapid synthesis of the needed protein)

113
Q

What is the 4th step of Translation

A

Peptide bonds form between each amino acid on the polypeptide chain. As each new amino acid arrives the ribosome moves along the mRNA along 3 bases and the next tRNA arrives with it complementary anticodon and aa and so on

114
Q

What is the 5th step of Translation

A

The tRNA with its complementary anticodon collects the appropriate amino acid when the anticodon on the rRNA “matches” up codon on mRNA it clicks in the correct amino acid to the next part of the sequence on the growing polypeptide chain. Codon-anticodon match=correct Amino acid delivered

115
Q

What is the 16th step of Translation

A

The polypeptide chain is released from the ribosome and “folds” into a 3D structure becoming a functional protein

116
Q

What is the 7th step of Translation

A

A STOP codon ends translation. (there are 3 stop codons)

117
Q

What are the 2 types of mutations

A

1) Chromosome mutations
2) Gene or point mutations

118
Q

What is a chromosome mutation

A

whole genes or complete chromosome changes

119
Q

What is a gene or point mutation

A

a change in the DNA base sequence

120
Q

What are the 2 main types of Gene/Point mutations

A

1) Base substitution
2) Base insertion or deletion

121
Q

What are the 3 types of base substitution

A

1) Silent/same sense
2) nonsense
3) missense

122
Q

What is a silent/same sense mutation

A

different base but no change in the amino acid because of code redundancy eg ATA and ATG both code for try (tyrosine)

123
Q

What is a nonsense mutation

A

the substitute base results in a stop codon which results in an early termination of a protein, major consequences

124
Q

What is a missense mutation

A

when a base is substituted that does affect the amino acid. It alters the protein shape. This means the protein cant function properly and it can disrupt metabolic pathways

125
Q

What is a base insertion or deletion mutation

A

This causes a frameshift i.e it alters all the codons that follow the insertion or deletion of a base. (MISSENSE MUTATION)

126
Q

Describe the difference between a ‘somatic mutation’ and a ‘gametic mutaiton’

A

A somatic mutation is an alteration of the DNA sequence and does not get passed down to offspring as it occurs in somatic (body) cells. Whereas a gametic mutations occur in the germ-line cell/egg & sperm producing cells.

127
Q

List 3 examples of mutagens

A

1) X-rays
2) UV radiation
3) Peroxides

128
Q

Distinguish between a mutagen and carcinogen

A

A mutagen is an environmental factor that changes the genetic material and increases the likelihood of a mutation. Whereas a carcinogen is a type of mutagen that causes cancer.

129
Q

Distinguish between haploid and diploid

A

Haploid means half only 1 set of chromosomes (n) whereas diploid means full, contains 2 sets of chromosomes (2n)

130
Q

Explain the term ‘autosomal recessive condition’

A

Autosomal recessive condition means the mutation has occurred in the gene on an autosome and not on a sec chromosome’s and it is recessive as the alleles are recessive.

131
Q

What is a frameshift

A

a change in bases that the ribosome reads