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Biology mine > proteins > Flashcards

proteins Flashcards

1
Q

What are peptides?

A

Polymers made up of amino acid molecules

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2
Q

What do proteins consist of?

A

One or more polypeptides arranged as a complex macromolecules
N,H,O

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3
Q

How many amino acids are found in cells
How many are non essential
how many are essential (why)

A

20
5
9 (body doesnt make them)

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4
Q

When do amino acids join together

A

When the amine and the carboxylic group, connected to the the central carbon atoms react.

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5
Q

How do amino acids join together

A

The hydroxyl in the carboxylic acid group of one amino acid reacts with hydrogen in a amine group of another amino acid

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6
Q

What bond is formed between two amino acids

A

Peptide bonds, making the compound dipeptide

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7
Q

What is produced as a peptide bonds two amino acids

A

Water molecule from condensation reaction

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8
Q

When amino acids are joined together by peptide bonds, what is formed?
What catalyses this reaction

A

Polypeptide

Peptidyl transferase- found in ribosomes

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9
Q

General structure of an amino acid

A

Amine group
R-grouo
Carboxyl group

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10
Q

Which part of the amino acid reacts with eachother

What do they form

A

R-groups

Different bonds

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11
Q

By the R-groups interacting with eachother, what did it result in

A

They made bonds which resulted in long chains of amino acids, folding into complex structures of proteins

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12
Q

What does the different sequences of amino acids allow for?

A

Different structures and shapes being produced

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13
Q

What is thin layer chromatography

A

Technique used to separate the individual components of amino acids

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14
Q

Describe the primary structure of proteins

A

The sequence which amino acids join, directed by information from the DNA. The particular amino acids in the sequence influence how polypeptides folds to give the proteins final shape.
Peptide bonds involved

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15
Q

Describe the secondary protein structure

A

oxygen,hydrogen and nitrogen atoms of the amino acids basic structure interact.
H bonds may form within amino acid chain, making it coil shaped- alpha helix
Polypeptide chains lie parallel to one another, joined by H
bonds- this makes it appear pleated- beta pleated sheet

Secondary structure is a result of H bonds and form regions along long protein molecules

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16
Q

Describe the tertiary structure

A

Folding of the protein into final shape
interactions from the secondary structure folding the chains brings the R groups closer together, allowing them to react:
-Hydrophobic and hydrophilic interactions- weak interactions between polar and nonpolar R groups
-Hydrogen bonds -weak bonds
-Disulfide bonds-strongest, covalent bonds
-Ionic bonds quite strong
These produce a variety of complex shaped proteins

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17
Q

Describe the Quaternary structure

A

This results from the association of two or more individual proteins- subunits
interact between different protein molecules

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18
Q

Where are proteins assembled?

A

In the aqueous environment of the cytoplasm

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19
Q

What factors are considered to decide the way a protein will fold

A

depends on whether the R groups are hydrophilic or hydrophobic
hydrophilic groups are on the outside of protein and hydrophobic on the inside

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20
Q

Describe how peptides breakdown

A

proteases- enzyme catalyses the reverse action turning peptides back into amino acids. water molecule used to break them -hydrolisis reaction.reforming amine and carboxylic group

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21
Q

Describe a globular protein

A

compact, water soluble and spherical protein

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22
Q

When do globular proteins form

A

They form when proteins fold into their tertiary structures in a way that the hydrophobic R groups on the amino acid are kept away from the aqueous environment.

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23
Q

How does the globular protein structure allow for solubility

A

hydrophobic R groups on the amino acid are kept away from the aqueous environment. The hydrophilic R-groups are on the outside of the protein - making it soluble

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24
Q

Why is solubility important in globular proteins?

A

Essential for regulating many processes necessary to life.

Like chemical reactions, immunity, muscle contraction

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25
Q

Example of a globular protein

A

Insulin

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26
Q

What does insulin do in globular proteins?

A

Regulates blood glucose concentration

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27
Q

What property do hormones need to be transported in the blood stream

A

Soluble

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28
Q

Hormones have to … into specific….on the cell…….to have an effect

A

Fit
Receptors
Surface membrane

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29
Q

What are conjugated proteins?

A

Globular proteins that contain non-protein components known as a prosthetic group

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30
Q

What are the different conjugated proteins known as

A

Lipids/carbohydrates join with proteins
Lipoprotein
Glycoprotein
metal ions

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31
Q

Give an example of prosthetic group

A

Haem groups, contain Fe2+

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32
Q

examples of haem groups

A

Catalase

haemoglobin

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33
Q

Describe haemoglobin

A

Red, oxygen carrying pigment found in red blood cells.
quaternary structure made of 4 polypeptides, 2 alpha, 2 beta subunits
Subunits contain haem groups- iron II present in haem groups- combine with oxygen reversibly.
Picks up oxygen in lungs and transport it to the cells, where its realised

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34
Q

What is catalyse?

A

An enzyme

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35
Q

What does the enzyme catalase do?

A

Increases reaction rates

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36
Q

Describe the structure of catalase

A

Quaternary protein containing 4 haem prosthetic groups.

The iron 2 ion in the prosthetic group allow for catalase to interact with hydrogen peroxide and speed up break down.

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37
Q

Dangers of hydrogen peroxide, what stops it

A

Damages cells and components if accumulates.

Catalase makes sure this doesn’t happen

38
Q

describe the structure of fibrous proteins

A

Long insoluble molecules form the high proportion of amino acids with Hydrophobic R groups.
Amino acid structure is repetitive

39
Q

Examples of fibrous proteins

A

Keratin
elastin
Collagen

40
Q

What do fibrous proteins make?

A

Stein long molecules which are not folded into a 3D structure

41
Q

Describe keratin

A

Fibrous protein in hair skin and nails
Large amount of sulfar containing amino acids- cysteine.
Strong disulfide bonds, making it insoluble and strong
More disulfide bonds= more Unflexible

42
Q

Describe elastin

A

Fibrous proteins found in elastic fibres
Present in Blood vessels and alveoli of lungs- allow for flexibility.
Quaternary protein made from tropoelastin(stretchy)

43
Q

Describe collagen

A

Fibrous protein
Connective tissue found in skin tendon ligaments and nervous system
Made of three polypeptides wound together in a long rope like structure.
Flexible

44
Q

What elements do nucleic acids contain

A

C’H’O and nitrogen and phosphorus

45
Q

What is a nucleotide made up of?

A 
Pentose monosaccharide(5 carbons) 
Phosphate group (-PO42-)
Nitrogenous base (2carbon ring structure)
46
Q

How are nucleotides linked

A

Condensation reaction to form polynucleotides

47
Q

When nucleotides join where does the covalent bond form

What’s the bond also referred to as

A

Forms a covalent bond between the the phosphate group at the 5th carbon of pentose sugar with
Hydroxyl group of the third carbon of pentose sugar
Phosphodiester bond

48
Q

Where do the Phosphodiester bonds form when nucleotides join

A

Along the sugar phosphate back bone with a base attached to each sugar

49
Q

How are the Phosphodiester bonds broken in the nucleotides

A

Hydrolysis

Realising individual nucleotides

50
Q

What does DNA stand for

A

Deoxyribose nucleic acid

51
Q

What bases are in DNA

A

Cytosine
Thymine
Adenine
Guanine

52
Q

What is a pyrimidines

A

Smaller bases containing single carbon ring structures

T and C

53
Q

What is a purine

A

Larger bases containing double ring structures

A and G

54
Q

What is DNA made up of

A

A few to a million nucleotides

Made of two strands of polynucleotides coiled into a helix

55
Q

What are the bonds in the double helix of DNA

A

Held together by H bonds between bases

56
Q

Describe the double helix

A

Each strand has a phosphate group at one end and a hydroxyl group at the other, the two strands run antiparallel

57
Q

What complimentary bases join together and how many bonds

A

CG- three H bonds
And
TA- form two H bonds

58
Q

This means that the small….base joins to the large….base

A

Pyrimidine

Purine

59
Q

What carried the genetic information to an organism in DNA

A

The sequence of bases in a code

60
Q

What does RNA stand for

What’s it’s essential role

A

Ribonucleic acid
Role in the transfer of genetic information from DNA to protein that make enzymes.
DNA can’t leave nucleus so mRNA transcribes it.

61
Q

How are RNA nucleotides different to DNA ones

A

Ribose sugar instead

T replaced by Uracil

62
Q

Why are RNA polymers small

A

So they can leave the nucleus and travel to the ribosomes for protein synthesis

63
Q

How does DNA replicate

A

DNA unzips by DNA helicase enzyme

Free nucleotides will then pair with their complimentary bases which are exposed when Strand separates

H bonds form between them

Once all lined up DNA polymerase joins them together

Two identical molecules of DNA have been made

64
Q

Why is jt called semi conservative replication.

A

Each DNA contains of one of the old strands of DNA and one of the new ones

65
Q

What happens if incorrect sequence

A

Mutation

66
Q

What does DNA code for

A

Amino acid sequences

Known as genetic code

67
Q

Instructions for DNA are carried in sequences of bases along chain of nucleotides, what is the code known as

A

Triplet code, sequence of three bases called codon

68
Q

What do codons do

A

Each one codes for an amino acid

69
Q

What is a complete sequence of bases to code for a protein called

A

Gene

70
Q

Describe the genetic code

A

Universal

All use the same code

71
Q

How many triplet codes or codons are possible

A

64

72
Q

What do codons act as

A

Start codon
Signals the start of sequence that codes for a protein.

Middle codon- codes for amino acid methionine

Stop codons- signals end of sequence

73
Q

Advantages for having a start codon

A

Ensures triplet code is ‘in frame’

74
Q

What is a degenerate code

A

A triplet code can code for more than one amino acid

There can be many different ones for each enzyme

75
Q

What protects DNA from being damaged in the cytoplasm

A

Double membrane that encloses the nucleus

76
Q

Why does transcription occur

A

DNA molecules are too large to leave nucleus so has to be copied and transcribed to site of protein synthesis- ribosome

77
Q

How does transcription happen

A

Section of DNA containing genes unzips from DNA helicase , beginning at the start codon
The sense strand running from 5 to 3 codes for proteins and the complimentary one doesn’t; antisense strand + acts as template strand during transcription so the complimentary RNA strand formed carries same base sequence as sense strand

Free nucleotides base pair with complimentary bases on the antisense streams when DNA unzips. (Uracil)

Phosphodiester bonds formed by RNA polymerase

Transcriptions stops at end of gene-mRNA
mRNA detaches from DNA template and leaves through nucleus pore and travels to ribosomes to cytoplasm

78
Q

What is a sense strand

A

the strand that codes for proteins

79
Q

Why is rRNA important

A

Maintains structural stability of protein synthesis sequence
Biochemical role in catalysing reactions

80
Q

What happens in translation

A

mRNA binds to specific site in the ribosomes
Ribosomes hold it in place why they translate and code it into amino acid sequence
tRNA’s anticodon beings to a complimentary codon on mRNA, following normal base pairing
When tRNA anticodons bind to complimentary codons along mRNA, the amino acids are brought together in correct sequence to form primary structure of protein

Amino acids added one by one and polypeptide chain grows

81
Q

What do ribosomes act as in translation

A

Binding site for mRNA and tRNA and catalyse the assembly of proteins

82
Q

What types of activities do cells require energy from?

A

Synthesis- molecules, proteins

Transport- pumping molecules across cell membrane by active transport

Movement- protein fibres in muscle cells causing contractions

83
Q

What does ATP stand for

A

Adenosine triphoaphate

84
Q

What is ATP made of

A

Nitrogenous base
Pentose sugar
Three phosphate groups

85
Q

What base does ATP use

A

Adenine

86
Q

How does ATP release energy

A

Small energy needed to break phosphate group which releases lots of energy when the phosphate group undergoes other reactions involving bond formation.

87
Q

What reaction is it that ATP undergoes

A

Hydrolysis reaction water used

88
Q

What is the equation for ATP

A

ATP + H2O -> ADP + Pi + energy

89
Q

What is ATP hydrolysed into?

A

Adenosine diphosphate

90
Q

Is ATO a good long term source?

What’s a better source

A

No as phosphate group is unstable

Carbohydrates fats

91
Q

How does cellular respiration create ATP

A

Reattached the phosphate group to and ADP molecule

Condensation reaction- water is removed

92
Q

Properties of ATP

A 
Small
Water soluble 
Contains bonds between phosphates with intermediate energy
Releases energy in small quantities 
Easily regenerated

Biology mine (6 decks)

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