B3

?
  • Created by: ireynolds
  • Created on: 02-05-17 16:15
Whats a nucleus? (animal cell)
It contains DNA in the form of chromosomes.
1 of 111
What is a cytoplasm?
Gel-like substance where most of the cell's chemical reactions happen.
2 of 111
What is a cell membrane?
It holds the cell together and controls what goes in an out.
3 of 111
What is a ribosome?
It's where proteins are synthesised.
4 of 111
What are mitochondria?
Where most of the reactions involved in respiration take place. As respiration provides energy for cell processes, cells that need lots of energy contain many mitochondria.
5 of 111
Why do liver cells contain many mitochondria?
As they carry out many demanding metabolic reactions.
6 of 111
Why do muscle cells contain many mitochondria?
As they need energy to contract and cause movement.
7 of 111
What features do plant cells have?
Nucleus, cytoplasm, chloroplasts, cell wall, vacuole and cell membrane.
8 of 111
What are chloroplasts? (pc)
Where photosynthesis happens.
9 of 111
What is the cell wall? (pc)
Made of cellulose and supports the cell.
10 of 111
What is a vacuole? (pc)
A relatively large structure that contains cell sap, a weak solution of sugar and salts.
11 of 111
What features do bacterial cells have?
Cytoplasm, cell membrane, cell wall. They have a single circular strand of DNA that floats on the cytoplasm, instead of a nucleus.
12 of 111
What are chromosomes?
Long molecules of coiled up DNA.
13 of 111
What shape is DNA?
A double helix.
14 of 111
What are each of the 2 strands of DNA made up of?
Small groups called nucleotides.
15 of 111
What does each nucleotide contain?
A small molecule called a base.
16 of 111
What are the 4 bases in DNA?
A, C, G & T
17 of 111
How are the DNA strands kept wound tightly together?
As each base forms cross links to a base on the other strand.
18 of 111
What bases pair with each other?
A & T C & G =called complementary base-printing.
19 of 111
What did Crick and Watson do in 1953?
First scientists to build a model of DNA.
20 of 111
What data from other scientists did they use to help them understand the molecule of DNA?
X-ray data showing it's a double helix formed from 2 chains. Other data showing the bases occurred in pairs.
21 of 111
How does DNA replicate itself?
DNA copies itself every time it divides. 1) It unzips to form 2 single strands. 2) New nucleotides join on using comlementary base-pairing. 3) Result= two double-stranded molecules of DNA that are identical to the original.
22 of 111
What controls the production of proteins?
DNA
23 of 111
What's a section of DNA that codes for a particular protein called?
Gene.
24 of 111
What are proteins made up of?
Chains of molecules called amino acids, each different protein has its own particular number and order of amino acids.
25 of 111
What does the shape of a protein give it?
A function.
26 of 111
What decides the order of amino acids in a protein?
The order of bases in a gene.
27 of 111
What is each amino acid coded for by?
By a sequence of three bases in the gene.
28 of 111
How are amino acids joined together to make proteins?
By following the order of bases in the gene. 1) there's a sequence of bases. 2) the cell reads the genetic code. 3) it puts the amino acids together.
29 of 111
Where are proteins made in the cell?
In the cell cytoplasm by tiny structures called ribosomes.
30 of 111
How does the cell get the code from the DNA to the ribosomes?
By using the molecule mRNA which is made by coping the code from DNA, the mRNA acts as a messenger between the DNA and ribosome, carrying the code between to two.
31 of 111
Why can't DNA move out of the cell nucleus?
Because it's too big.
32 of 111
Why do different types of cell have different functions?
Because they make different proteins.
33 of 111
Why do cells only make certain proteins?
Because only some of the full set of genes is used in any one cell. Some genes are 'switched off' which means the proteins they code for aren't produced.
34 of 111
What do genes that are 'switched on' do?
Determine the function of the cell. E.G; in a muscle cell, only the genes that code for muscle cell proteins are switched on.
35 of 111
What are the four main types of proteins?
Enzymes, carrier molecules, hormones, structural proteins.
36 of 111
What do carrier molecules do?
Used to transport smaller molecules E.G; haemoglobin binds to oxygen molecules and transports them round the body.
37 of 111
What do hormones do?
Used to carry messages around the body E.G; insulin released to regulate blood sugar levels.
38 of 111
What do structural proteins do?
They are physically strong. E.G; collagen strengthens connective tissues.
39 of 111
What are enzymes?
Biological catalysts that speed up chemical reactions in the body.
40 of 111
Advantages of enzymes?
Reduce the need for high temperatures (which can damage cells) and we only have them to speed up the useful chemical reactions in the body.
41 of 111
Does every different biological reaction have its own enzyme designed for it?
Yes.
42 of 111
Why are enzymes different?
Each enzyme is coded for by a different gene and has a unique shape which it needs to do its job.
43 of 111
What's the substrate?
The molecule changed in a biological reaction.
44 of 111
What's an enzymes active site?
The part where it joins on to its substrate to catalyse the reaction.
45 of 111
What does an enzyme having a high specificity for their substance mean?
That they're really picky and only work with one substrate.
46 of 111
Why do enzymes have a high specificity for their substrate?
Because, for the enzyme to work, the substrate has to fit the active site, if the substrate doesn't match the active sites shape, then the reaction won't be catalysed. Called the 'lock and key' mechanism, as they fit perfectly.
47 of 111
What does changing the temperature do to an enzyme-catalysed reaction?
Changes the rate of the reaction.
48 of 111
What does a higher temperature do to the rate of an enzyme-catalysed reaction?
A higher temp increases the rate at first, as more heat means the enzymes and the substrate particles have more energy, making the enzymes and the substrate particles move about more and have a higher collision rate.
49 of 111
What effect does a lower temp have on it?
Lower collision rate and so a slower reaction.
50 of 111
What happens if the temperature gets too hot?
Some of the bonds holding the enzyme together will break. The enzyme will become denatured.
51 of 111
What is a denatured enzyme?
Where it loses it's shape and it's active site doesn't fit the shape of the substrate anymore. Therefore it can't catalyse the reaction and stops; the enzyme can't function. The change in shape is irreversible.
52 of 111
What is an enzymes optimum temperature?
When the reaction goes fastest, just before it gets too hot and starts the denature.
53 of 111
What's human enzyme optimum temperature?
About 37degrees which is body temperature.
54 of 111
What effect does ph have on enzymes?
If the ph is to high or low, it interferes with the bonds holding the enzyme together, changing the shape of the active site and denaturing it.
55 of 111
What's an optimum ph for enzymes?
Theph that they work best at. Usually ph7; neutral.
56 of 111
What's pepsin?
An enzyme used to break down proteins in the stomach,working best at ph2 so it's suited for the acidic conditions.
57 of 111
What does a Q10 value for a reaction show?
How much the rate changes when the temp is raised by 10degrees.
58 of 111
Equation for the Q10 value?
Q10 = rate at higher temperature/rate at lower temp.
59 of 111
What would a Q10 value of 2 mean?
That the rate doubles when the temp is raised by 10degrees. And 3 means trebles ect...
60 of 111
What are gene mutations?
A change in the DNA base sequence.
61 of 111
What could happen if a mutation occurs within a gene?
Could stop the production of the protein the gene normally codes for, or mean a different protein is produced instead.
62 of 111
Bad effect of a mutation occuring in a reproductive cell?
The offspring might develop abnormally or die at an early stage of development.
63 of 111
Bad effect of a mutation occuring in a body cell?
The mutant cells can start to multiply in an uncontrolled way and invade other parts of the body; cancer.
64 of 111
Possible benefits of a mutation?
A protein is produced that's an improvement of what it was supposed to be, giving the organism a survival advantage over the rest of the population, and can pass it on to it's offspring.
65 of 111
Why are some mutations neither harmful nor helpful?
As the don't change the protein being coded for, so have no effect on the organism.
66 of 111
How do mutations occur spontaneously?
When a chromosome doesn't copy itself properly.
67 of 111
What increases the chance of mutation if you're exposed to it?
1) Ionising radiation(x-rays, uv, radioactive substances) the greater the dose, the higher the chance. 2) Certain chemicals called mutagens, if they cause cancer they're called carcinogens.
68 of 111
What's an example of a carcinogen?
Cigarette smoke .
69 of 111
Advantages of being a multicellular organism?
Be bigger, cell differentiation, more complex.
70 of 111
Advantages of being able to be bigger?
Can travel further, get nutrients in variety of different ways, fewer things can eat or squash you.
71 of 111
Advantages of cell differentiation?
Can have different cells for different jobs, and cells can be specially adapted to do the jobs E.G; carrying oxygen in blood.
72 of 111
Advantages of being complex?
Have specialised organs, different shapes,behaviour and can be adapted specifically to their particular environment.
73 of 111
What does a multicellular organism have to have?
Specialised organ systems.
74 of 111
What types of specialised organ systems do they have to have?
A system to communicate between cells(nervous system), system to supply cells with nutrients they need(circulatory system), a system that controls exchange of substances with environment(respiratory system).
75 of 111
What is mitosis?
When a cell reproduces itself by splitting to form two identical offspring.
76 of 111
When does mitosis happen?
When you want identical cells(When you want to grow,m or to replace worn-out cells to repair tissues).
77 of 111
What happens to the DNA in mitosis?
1) Before mitosis starts the DNA in the cell is replicated. 2) The the beginning, the DNAcoils into double armed chromosomes which are exact copies of each other. 3) The chromosomes line up at the centre of the cell and divide as fibres pull them ...
78 of 111
continued....
...divide as cell fibres pull them appart. 4) the2 arms of each chromosomes go to opposite poles of the cell. 5) Membrames form around each of the sets of chromosomes.
79 of 111
continued...
6) The cytoplasm divides leaving 2 genetically identical cells. 7) process repeats to divide again.
80 of 111
What's meiosis?
Cell division in which gametes are formed.
81 of 111
What are gametes?
Sex cells, eggs and sperm.
82 of 111
What are the body cells of mammals?
Diploid.
83 of 111
What does diploid mean?
That each of the organisms body cells has two copies of each chromosome in it's nucleus. One from the father and one from the mother.
84 of 111
What kind of cells are haploid in mammals?
Gametes.
85 of 111
What does a cell being haploid mean?
That they only have one copy of each chromosome.
86 of 111
Why are gametes haploid?
So when the egg and sperm combine, they'll form a cell with the diploid number of chromosomes.
87 of 111
Explain the process of meiosis?
1)DNA replicates and curls to form double-armed chromosomes. 2)The chromosomes arrange themselves into pairs. 3)In the first division the pairs split up and the chromosomes in each pair move to opposite cell poles...
88 of 111
continued...
4)In the two knew cells there's no pairs and it's a mixture of the mammals mum and dads genes totally 23 chromosomes instead of 46. 5)In the second division each chromosome splits apart, and one arm end ends up in a different cell= 4 new cells.
89 of 111
continued...
5) Each of the 4 cells in genetically different as the chromosomes get shuffled up, leaving each gamete with a random selection of half the chromosomes.
90 of 111
What's a zygote?
A diploid cell formed in fertilisation when male and female gametes combine.
91 of 111
What are the characteristics of the zygote controlled by?
The combination of genes on its chromosomes. As it's inherited features from two parents it will show features of both, but not exactly like either of them.
92 of 111
What is a sperm cells function?
To transport the male's DNA to the female's egg.
93 of 111
How are sperm cells adapted for their function?
Are small with long tails to assist the swim to the egg, lot's of mitochondria to provide energy for the swim. Have an acrosome at the head which can release the enxymes needed to digest their way though the egg cells membrane.
94 of 111
How do animals grow?
Grow until reach a finite size. Growth happens by cell division.
95 of 111
How do plants grow?
Grow continuously. They grow in height by cell enlargement (elongation). Growth by cell division happens in areas of the plant called meristems(tips of roots and shoots).
96 of 111
What's cell differentiation?
Process by which a cell changes to become specialised for a job.
97 of 111
Does differentiation occur in animal cells?
Yes but lost at an early stage.
98 of 111
Does differentiation occur in plant cells?
Yes and the ability is never lost.
99 of 111
What are undifferentiated cells?
Ones that can develpoe into other types of cells, tissues and organs depending on instruction, they're named stem cells.
100 of 111
Where are stem cells found?
In early human embryos, or in adult human bone marrow , but they aren't as vertisile and can only turn into a few types of cells.
101 of 111
How are stem cells already used in medicine?
Bone marrow transplants to cure blood disorders,
102 of 111
What are possible uses for human stem cells in medicine?
EXtracting stem cells from embryos and growing them, to eventually grow tissues to treat medical conditions. E.G; nerve cells for brain damage and spinal injuries, skin cells for skin grafts, known as stem cell therapy.
103 of 111
Why are people against stem cell research?
As they feel human embryos shouldn't be used in experiments as they're potential human lives.
104 of 111
Why are people for stem cell research?
Curing existing patients who are already suffering is more important than the embryos. The embryos used in research are unwanted ones and would otherwise be destroyed.
105 of 111
Explain the method of measuring growth by length?
Just measuring length or height of an organism.
106 of 111
Advantages of this method?
Easy and no skilled workers or specialist equipment needed.
107 of 111
Disadvantages of this method?
Only tells you about one change, missing out changes in width, diameter, number of branches ect...
108 of 111
Explain the method of measuring growth by wet mass?
Weigh the plant or animal as it comes.
109 of 111
Advantages of this method?
Easy to measure.
110 of 111
Disadvantages of this method?
Wet mass is very changeable. E.G; plant will be heavier if it's recently rained as absorbed lots of water, and heavier if eaten or drank.
111 of 111

Other cards in this set

Card 2

Front

What is a cytoplasm?

Back

Gel-like substance where most of the cell's chemical reactions happen.

Card 3

Front

What is a cell membrane?

Back

Preview of the front of card 3

Card 4

Front

What is a ribosome?

Back

Preview of the front of card 4

Card 5

Front

What are mitochondria?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

B3d-f
B3a-c
See all Biology resources »See all B3 resources »