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Biology > 2.1.3 nucleic acids and 2.1.4 Enzymes > Flashcards

2.1.3 nucleic acids and 2.1.4 Enzymes Flashcards

1
Q

Biological catalysts

A

catalysts in living organisms
work at lower temp and pressure to chemical catalysts
speeds up reaction without being used up

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2
Q

what type of protein are enzymes

A

globular
specific shape
water soluble

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3
Q

what do enzymes do to the activation energy of a reaction

A

decrease it
less energy needed to start a reaction
provide alternative pathway by holding reacting groupps close together or put strain on the bonds

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4
Q

Anabolic reactions

A

enzymes make large molecules out of smaller ones

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5
Q

Catabolic reactions

A

break large molecules into smaller ones

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6
Q

metabolism

A

sum total of all reactions happening in cell or organism

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7
Q

metabollic pathway

A

essential process for life

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8
Q

Intracellular enzymes

A

enzymes produced and act inside the same cell

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9
Q

extracellular enzymes

A

enzymes act outside the cell in which they were produced

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10
Q

why is extracellular enzymes neccessary

A

large molecules cant fit into the cell directly through the plasma membrane

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11
Q

example of intracellular enzyme

A

catalase
ensure hydrogen peroxide is broken down to oxygen and water

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12
Q

example of extracellular enzyme

A

digestion
break large molecules into smaller ones

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13
Q

Amylase

A

produced by salivary glands and pancreas
released into saliva and pancreatic juice
breaks down starch polymers into maltose

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14
Q

trypsin

A

a protease
digestion of proteins into smaller peptides which can be further broken down into amino acids

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15
Q

lock and key hypothesis

A

substrate fits into active sit of only one enzyme
when substrate binds it forms enzyme substrate complex
products are produced and released

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16
Q

induced fit hypothesis

A

substrate cause enzyme to change shape slightly as it binds
shape of active site is NOT fixed

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17
Q

Active site

A

made of 6-10 amino acids

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18
Q

precursor activation

A

the activation of an inactive enzyme

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19
Q

how can enzymes be activated

A

change to their tertiary structure
change in their enviroment
addition of a non protein helper (cofactor)

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20
Q

cofactors

A

non protein molecule that binds to an enzyme to activate it
An enzyme that needs one can’t function without it

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21
Q

3 types of cofactors

A

prosthetic groups
inorganic ions
coenzymes

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22
Q

prosthetic groups

A

bind tightly to become a permanent part

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23
Q

coenzyme

A

bind loosely

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24
Q

enzyme activity definition

A

indicates the rate of reaction catalysed by the enzyme expressed

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25
factors that affect enzyme activity
temperature ph enzyme concentration substrate concentration
26
why is rate not controlled
start particles move fast collide making lots of enzyme substrate complexes reaction slows as less available to collide reaction stops when all are used up
27
inhibitors
a molecule that binds to enzymes to prevent them carrying out their catalytic functions slow down rate of enzyme controlled reactions
28
competitive inhibitors
molecule with simular shape to active site binds blocks substrate binding less enzyme substrate complexes formed reduced rate of reaction
29
non competitive inhibitors
bind to allosteric site causing change to tertiary structure active site changes shape so substrate is no longer complementary less ESC's formed
30
reversible binding
binds temporarily non covalent enzyme goes back to normal
31
irreversible binding
permanent binding covalent permanently changed
32
product inhibition
product of reaction inhibits enzyme involved in that reaction can be competitive or non competitive always reversible
33
DNA
deoxyribonucleic acid found in nucleus carries code to make all proteins in body
34
RNA
ribonucleic acid used to make proteins 3 forms - messenger , transfer, ribosomal
35
structures of nucleotide
phosphate pentose sugar nitrogenous base
36
how are nucleotides linked together
condensation reaction phosphate group at 5th carbon of pentose sugar forms covalent bond with hydroxyl group at 3rd carbon of pentose sugar of adjacent sugar forms phosphodiester bond
37
name of bond between nucleotides
phosphodiester
38
pyrimidines
smaller bases which contain single carbon ring structures Thymine and cytosine
39
purines
larger bases which contain double carbon ring structures adenine and guanine pure as gold (Ag)
40
ATP structure
3 phosphate groups ribose sugar adenine base
41
formation of ADP
hydrolysis reaction of ATP where water used to split bond between 2nd and 3rd phosphate group releasing the phosphate group Pi and a small amount of energy
42
reaction to convert ADP back to ATP
add energy from food to re join bond ADP add Pi phosphate group re joins releasing a water molecule condensation reaction
43
structure of dna
double helix made of 2 anti-parallel DNA nucleotides held together by hydrogen bonds between complementary base pairs
44
sense strand definition
contains genetic code for protein
45
antisense strand definition
acts as a template strand for transcription runs 3' to 5' complementary to sense strand
46
complementary base pairing rules
adenine and thymine form 2 hydrogen bonds cytosine and guanine form 3 hydrogen bonds
47
which parts of dna are hydrophobic
nitrogenous base
48
which parts of dna are hydrophilic
phosphate group
49
chromosome definition
long strand of dna made up of many genes
50
chromatin
chromosomes wrapped around histones
51
histones
proteins dna's wrapped around it
52
gene
short section of dna that codes for a particular protein
53
dna extraction practical method
crush strawberry using pestle and mortar with 20cm3 dna extraction buffer strain into beaker using tea strainer and muslin pour filtrate into boiling tube add 5cm3 ethanol let stand for 5 minutes dna will form white precipitate on top layer use inoculating loop to scoop out
54
why is strawberry crushed
to break up cells
55
function of adding detergent to strawberry
break up cell wall and phospholipid bilayer
56
function of adding protease enzyme during dna extraction
break down histones to separate from dna
57
function of adding salt during dna extraction
helps make it less soluble
58
function of adding ethanol during dna extraction
to make dna become visible
59
what is DNA replication and when and where does it take place
copying of dna happens in the nucleus immediately before mitosis in late interphase
60
semi conservative replication definition
each daughter DNA molecule has one new and one old strand
61
DNA replication steps
dna helicase unwinds dna molecule and travels along it breaking the hydrogen bonds between complementary base pairs makes 2 single strands each strand acts as template for assemble of new complementary strand free dna nucleotides attract to exposed bases on template strand and hydrogen bonds form between them DNA polymerase travels along new strand catalysing the joining of nucleotides by phosphodiester bonds each new dna molecule has one new and one old strand
62
where do the free dna nucleotides come from in dna replication
cytoplasm
63
conservative dna
dna copied and get one new strand
64
dispersive replication
dna is cut into several parts and each section is copied and reattached to produce 2 molecules
65
Experiment on bacteria for DNA replication
1- heavy nitrogen growth medium . bacteria uses heavy nitrogen to synthesis new dna 2- moved into light nitrogen medium. Bacteria uses light nitrogen to synthesis nitrogenous bases in dna. Band moves slightly up tube 3- still in light nitrogen. 2 molecules are now made of light nitrogen if carried on more pure light nitrogen will be forms but 2 molecules will still always have only 1 strand of light
66
what is the genetic code
code that determines the order of amino acids in each and every protein in all living things
67
where is the genetic code found
our DNA in the nucleus mRNA that goes to ribosome for protein synthesis
68
why is there 2 versions of the genetic code
1st version allows you to translate dna 2nd version allows you to translate rna
69
triplet
3 bases codes for one amino acid
70
what is the genetic code described as
triplet non-overlapping degenerate universal
71
Non-overlapping for genetic code
each base is read in only one triplet /codon
72
degenerate in terms of the genetic code
each amino acid has more than one triplet code that codes for it
73
what does it mean by the genetic cod is universal
same code used for all living things
74
gene
short section of DNA that codes for a specific protein
75
why don't ribosomes go straight into the nucleus to make the protein
dna might get damaged ribosomes needs single strand whereas dna is double stranded
76
overview of transcription
genes copied from dna to mrna happens in nucleus
77
overview of translation
happens in ribosomes code on rna is used to assemble the amino acid in the correct order to make protein
78
steps for protein synthesis
transcription and translation
79
messenger RNA
carries code from gene to ribosome
80
ribosomal RNA
joined with protein to form ribosome small subunit binds to mRNA
81
transfer RNA
amino acid on it is specific to each tRNA anticodon brings amino acid to mRNA in translation
82
steps in transcription
dna is unwound by dna helicase dna helicase travels up centre of dna breaking the hydrogen bonds to form 2 separate strands antisense strand is used as template (3' to 5') free RNA nucleotides base pair with complementary bases on template strand Uracil replaces thymine RNA polymerase catalyses formation of phosphodiester bonds continues util end of gene mrna leaves nucleus via nuclear pore and goes to ribosome
83
where does translation occur
ribosome
84
translation steps
end of mRNA binds between small and large subunits of ribosome ribosome moves along mRNA until finds start codon tRNA with complementary anticodon to start codon binds to mrna another trna with complementary anticodon to nxt codon binds the 2 amino acids then form a peptide bond this releases the 1st amino acid this repeats until stop codon is reached and then the ribosome becomes detached from polypeptide chain
85

Biology (25 decks)

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