science B3

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where do most reactions take place in a cell?
Cytoplasm .it may contain mitochondria which is where respiration happens
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what controls movement out of a cell?
cell membrane
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where does respiration take place?
in the mitochondria
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what is DNA?
nucleus of each cell contains complete set genetic code ,information carried by genes on chromosomes which are long coils called DNA.
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what does genetic code control?
cell activty and some charecteristics of whole organism
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what is the genetics code formed of?
four bases a+t ,c+g with g on opposite sides of strands which bond to hold two strands of DNA together
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who put forward DNA in 1953?
james watson and francis crick
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where are proteins made ?
made in the cytoplasm
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how does the cell make proteins ?
the cell uses amino acids from food to construct proteins
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what does gene in a molecule contain?
different sequences of bases
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what does DNA Control & what is it short for ?
cell function & Deoxyribonucleic acid
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how does DNA control cell function?
by controlling the production of proeteins some of which are enzymes
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what does the sequence of bases in a gene represent ?
the order in which the cell should assemble amino acids to make the protein
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how many bases represent one amino acid in a protein chain?
three
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what does each protein have & what is it made of?
different shape and function & chains of amino acids
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what are proteins synthesized by & where are they located ?
ribosomes in cytoplasm
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in order for code in the nucleus to be translated as a new protein by ribosomes a ....... needs to travel from cytoplasm then attach to a ribo some?
"messenger" molecule called mRNA
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how is mRNA constructed ?
from DNA template in the nucleus
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what does mRNA carry into the cytoplasm and attach to a ribosome ?
code from original DNA
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what does the ribosome translates the code on?
mRNA
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what does then mRNA do ?
constructs a sequence of amino acids
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what does a long chain of amino acids become?
a protein
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what is released from a ribosome to carry out its function?
protein
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why are proteins neded in cells?
they are a vital component in the construction of membranes
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whats collagen ?
a structural protein found in connective tissue
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whats insulin ?
hormone that helps to control blood sugar levels
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whats haemoglobin ?
carrier protein ,found in red blood cells ,which binds with oxygen
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what are enzymes ?
control chemical reactions in the body
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what does each proteins have ?
own number of sequence of amino acids
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what does this mean for each molecule?
different shapes of molecule
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what the estimate of different proteins in the human body?
19,000 with different particular functions
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what do enzymes act as?
biological catalysts
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what do biological catalyst do ?
speed up chemical reactions.including those that take place in living cells
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what reactions take place in a cell?
some are respiration,photosynthesis,and protein synthesis .
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why are enzymes highly specific ?
each one speeds up a particular reaction
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what do enzymes have ?
active sites
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what happens when a region of the enzyme molecule binds to a substrate molecule ?
the region binds to the substrate molecule and allows it to be temporarily changed
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what 2 thing do you have to change to affect the rate of reaction catalysed by an enzyme?
temperature and pH
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what does a rise in temperature do to the activity of the enzymes ?
increase the number of collisions between reactants and enzymes until a certain temperature
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what happens when the optimum temperature is reached?
permanently damage the enzyme molecules,decreasing or stopping the enzyme avticity.
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what temperature do the human body enzymes work best at and why?
37 °C because it human body temperature
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what is the "lock and key mechanism"?
when each enzyme has a different number and sequence of amino acids which gives it a unique 3D shape
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what are enzyme molecules denatured by?
high temperatures and extreme pH
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what does denatured mean ?
the bonds in the protein break and the shape of its active site is changed irreversibly .so the lock and key mechanism no longer works
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what happens at lower optimum temperatures to an enzyme ?
the enzyme is not at optimum so does not collide as often with substrate molecules so the rate of reaction is lowered
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what happens if the base sequence changes ?
result in production of different proteins in which new forms of GENES may arise from mutations in existing GENES
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are mutations harmful?
mutations are usually harmful or may have no effect whatsoever
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how can a mutation become beneficial?
if a new protein functions better
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how is a mutations frequency increased ?
ultra violet light,x-rays ,radioactive,certain chemicals
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whats a gene thats not expressed called ?
"switched off"
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what will a switched off gene do?
eventually turn on and determine the function of the cell
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what are mutations?
change to the structure of the DNA molecule
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what do mutations do ?
change or prevent the sequence of amino acids that the genes usually code for ,so different proteins are made
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what do living cells need and most when?
energy to function and most during exercise
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Other cards in this set

Card 2

Front

what controls movement out of a cell?

Back

cell membrane

Card 3

Front

where does respiration take place?

Back

Preview of the front of card 3

Card 4

Front

what is DNA?

Back

Preview of the front of card 4

Card 5

Front

what does genetic code control?

Back

Preview of the front of card 5
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