Biology 2 - Topic 1

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Give 4 things in the animal cell
Nucleus, Cytoplasm, Cell Membrane and Mitochondria
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Give 7 things in a plant cell
Rigid cell wall, Large vacuole, Chloroplasts, Nucleus, Cytoplasm, Cell Membrane and Mitochondria
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What does the nucleus do?
It contains the DNA and controls what the cell does.
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What does the cytoplasm do?
It is a gel-like substance where chemical reactions take place
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What does the cell membrane do?
It holds together the cell and controls what goes in and out of the cell.
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What does the mitochondria do?
This is where respiration happens and respires energy for the cell to work.
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What does the cell wall do?
Gives the cell support
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What does the vacuole do?
Contains cell sap which is a weak substance of salt and sugar
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What does the chloroplast do?
Where photosynthesis happens and contains chlorophyll.
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Give 4 things in a bacterial cell?
Chromosomal DNA, Plasmids, Flagellum and Cell wall.
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What does the chromosomal DNA do?
Controls the cell's activities and floats in the cell - NO NUCLEUS
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What does plasmids do?
These are small loops of extra DNA that contains genes for drug resistance.
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What does the flagellum do?
It is a long hair-like structure that helps the bacteria move.
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What can microscopes do?
Help you see things the naked eye doesn't.
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What do light microscopes do and when where they invented?
Lets us see things like: nuclei, chloroplasts and mitochondria. In 1590s.
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What do electron microscopes do and when where they invented?
Let you see smaller things in more detail, like: mitochondria, plasmids and chloroplasts. In 1930s.
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How do you calculate magnitude?
Length of image / Length of specimen.
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What is the DNA shape?
A double helix.
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What are the bases called?
Adenine, thymine, guanine and cytosine.
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What bases goes to which base?
A-T, C-G
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What is this called?
Base paring.
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What are the base pairs joined together with?
Weak hydrogen bonds.
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What is a gene?
A section of DNA
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What is a sequence of bases?
The code for a specific protein.
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Who discovered the structure of DNA?
Watson, Crick, Franklin and Wilkins.
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What did Franklin and Wilkins do?
They found that DNA has a helical structure by directing beams of x-rays onto DNA.
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What did Watson and Crick do?
They found that A and T where base pairs and as where C and G. They made the model of the DNA molecule.
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What practical can you do to extract DNA from cells? Step 1
Chopping up some onion and put in a beaker of detergent and salt that breaks down the cell membrane and, the salts stick to the DNA.
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Step 2 of the experiment.
Put the beaker ion 60 degree what for 15 mins. This denatures the enzymes and softens the onion cells.
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Step 3 of the experiment.
Put beaker in ice cool mixture that stops the DNA from breaking down.
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Step 4 of the experiment.
Put in a blender for few seconds and open the cell walls, which will release the DNA.
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Step 5 of the experiment.
Filter the mixture to get the big bits out.
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Step 6 of the experiment.
Add some ice-cool alcohol in the mixture and the DNA will come of the substance. It is stringy and white.
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How do cells make proteins?
String amino acids together.
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How many 1,000 of proteins are made with .... amino acids?
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What is the order of the bases?
The order in which the amino acids string together.
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What is a set of 3 bases called?
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What does DNA determine?
Which genes are switched on or off and so which proteins are made.
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What do some proteins help make that aren't made of proteins?
Substances form your diet: fats and minerals.
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Where are proteins made in the cells?
The ribosome.
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What is an mRNA molecule?
A single stranded molecule that is shorter and thinner to DNA.
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Describe the Transcription step in protein synthesis.
The DNA un-zips to be a template for mRNA. Base paring ensures it is complementary, which means that it is an exact match of the opposite strand.
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Describe the next two steps.
The mRNA moves out of the nucleus and into the ribosome. Amino acids that match the mRNA molecule and is brought to the ribosome by tRNA.
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Describe the translation step.
The ribosome sticks the amino acids together to main a chain called polypeptide. This is a triplet called codons.
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What are mutations?
It is a change in the organisms DNA sequence that may affect the amino acids by changing the: shape and the function.
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Why might mutation be harmful? Give an example.
A mutation could cause a genetic disorder. Cystic fibrosis.
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Why might a mutation be beneficial? Give an example.
A mutation can produce new characteristics that benefit the organism. Resistant to antibiotics.
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Why might a mutation be neutral. Give an example.
Some mutations can neither harmful or beneficial. Don't affect protein's function.
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What are enzyme?
Enzymes are catalysts produced by living organisms. They act as a biological catalyst.
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What can you raise to increase the reaction. Give an advantage and a disadvantage.
By increasing the temperature. It increases the wanted reactions and the unwanted reactions.
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What is a catalyst?
A catalyst increases the speed of the reaction without wasting energy or being used up.
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Enzymes are...
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What do enzymes do in DNA replication?
They help copy the DNA before it divides into mitosis or meiosis.
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What do enzymes do in protein synthesis?
They hold the amino acids together and form bonds between them.
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What do enzymes do in digestion?
They are secreted from the gut to digest food molecules.
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What is the substrate?
The molecule changed in the reaction.
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What is an active site?
The place where they enzymes joins together to the substrate.
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If the active site doesn't fit into the enzyme, what happen?
The reaction won't be catalysed - sped up.
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What is the 'lock and key' mechanism?
Where the substrate fits into the active site and, the enzyme increases the reaction. This produces the product quicker.
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How can you measure the rate of an enzyme - practical?
Measure the reaction by using amylase and the starch as the substrate. The amylase breaks down the starch and time how long it takes. Put a drop of iodine- if blue, starch is there and it has broken down.
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Give 3 variables of measuring enzymes.
temperature, pH and substrate concentration.
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Describe what happens when an enzyme is present in the substrate and the temperature rises.
The higher the temperature, the quicker the reaction. Until, it gets to the optimum temperature where the reaction won't increase. If it gets too hot, the enzymes lose shape and the active site doesn't fit - enzyme is denatured.
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What is denatured?
When an enzyme won't go back to it's original form if cooled down.
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What the hottest temperature for when enzymes become denatured in the human body?
37 degrees celcius.
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Describe what happens when the pH increases.
The higher the pH, the quicker the reaction until, it has reached it's optimum pH where no more reactions take place - active site denatured. (usually 7)
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describe what happens when the substrate concentration increases.
The higher the concentration, the quicker the enzyme until, it reaches its optimum concentration - all the active sites are full and nothing happens when you add more.
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What is the Human Genome Project?
Scientists from around the world worked together to find all the genes in the human body - 25,000.
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How many chromosomes do humans have?
46/ 23 pairs.
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Give 4 advantages of the Human Genome Project.
1. Predicts and prevents diseases. 2. Develops new and better medicine. 3. Accurate diagnosis. 4. Improves forensic science.
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Describe predicting and preventing.
When doctors know what genes are for which disease they can give advice on how to improve life style: diet, exercise.
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Describe developing new and better medicine.
Getting better treatment means that we know more about diseases and more effective medicine.
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Describe accurate diagnosis
Some diseases are hard to test for so, if we new the genetic cause, it is easier.
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Describe improving forensic science.
Forensic scientists can tell who the person is from DNA fingerprints so, in the future; we could get what the criminal looks like from the DNA.
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Give 3 disadvantages of the Human Genome Project.
1. Increases stress. 2. Gene-ism. 3. Discrimination.
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Describe increase of stress.
If someone knew that they where going to die, they could panic every time they had something wrong with them.
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Describe Gene-ism.
People could be scared on passing on their genes.
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Describe discrimination.
Life insurance could be very expensive or hard to get is they knew you could die from an illness.
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Genetic engineering use enzymes to...
...cut and paste genes.
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What is genetic engineering?
This is cutting out genes from one organism and putting them into other gene.
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What does genetic engineering produce?
Genetically modified organisms.
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Give 3 advantages on genetic engineering.
1. Reduces vitamin A deficiency. 2. Produces human insulin. 3. Increases crop yield.
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Describe reducing vitamin A deficiency.
Beta-carotene makes vitamin A. so, in places like Africa, children can go blind to vitamin A deficiency. Golden rice contains two genes which produce beta-carotene - makes less people have vitamin A deficiency.
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Describe producing human insulin.
Lots of insulin can be made quickly to help treat diabetes.
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Describe increasing crop yield.
GM crops are made to resist herbicides. If you spray field crops with herbicide, all the plants, except from GM, will increase crop yield.
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Human body cells are diploid or haploid?
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What is diploid cells?
They create two versions, one from mother and one from father.
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What is mitosis?
When a cell divides to create two identical cells with the same number of chromosomes - 46.
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Why does mitosis occur?
To repair and grow damaged tissues.
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Describe the 1st step in mitosis.
The DNA duplicates which causes an X-shaped chromosome.
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Describe the 2nd step in mitosis.
The chromosomes line up into the center of the cell and gets pulled apart by cell fibers.
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Describe the 3rd step in mitosis.
Membranes form around each set of chromosomes.
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Describe the 4th step in mitosis.
The cytoplasm divides. The cells are now genetically identical.
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What is asexual reproduction?
Organisms reproducing with mitosis.
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Give an example of an organism that reproduces asexually.
Strawberry plants.
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What is: 'no genetic variation'?
Where the offspring has the same genes as the parent.
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What are gametes?
They are sex cells called ova (females) or sperm(males). During sexual reproduction, two gametes combine to form a new cell; to become a new organism.
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Are gametes diploid or haploid?
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What is meiosis?
It is when 4 new cells are made but, half of the chromosomes are there.
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When does meiosis occur?
In reproductive organs: ovaries or testes.
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Describe the 1st division in meiosis?
It duplicates DNA and creates X-shaped chromosomes. The chromosomes line up in the center of the cell which gets pulled apart by cell fibers. The chromosomes are half in one cell and half in the other cell. There is a mixture of parents cells.
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What are alleles?
The mixing up of the father and mother cells, offspring variation.
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Describe the 2nd division.
The chromosomes line up in the center, gets pulled apart by cell fibers and divides. This creates 4 cells. They only have a single set of chromosome.
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What is cloning mammals?
A type of asexual reproduction where the cells are genetically identical.
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Describe what happens.
An unfertilised egg cell removed from nucleus and an adult cell removed from other female. Diploid nucleus inserted into egg. Electric shock on egg and divides by mitosis. They embryo is planted into female.
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What is an embryo?
A group of cells.
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Give an example this type of cloning.
Dolly the Sheep.
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Give 3 advantages.
Helps with shortage of transplants, understanding of embryos increased and preserve endangered species.
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Give 3 disadvantages.
1. Reduces gene pool. 2. Life expectation. 3. risks.
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Describe reducing gene pool.
If the population is closely related, there will a big wipe out if a disease occurs.
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Describe the life expectation.
Dolly was put down at 6 because she had old sheep genes: arthritis - maybe just an unlucky gene.
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Describe the other risks.
Cloning often fails, it causes genetic defects and immune system isn't as good - suffer from more diseases.
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Embryonic stem cells can turn into...
...any type of cell.
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Describe the procedure of stem cells.
1. Dividing by mitosis in a fertilised egg cell to create an embryo. The cells are undifferentiated. The cells divide to produce more cells that are specialised cells. This is done by the embryo starting to recogonise human organs and systems.
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What does differentiate mean?
The stem cells are all the same.
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What does specialised mean?
All the stem cells are the different.
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Give an example of specialised stem cells.
Blood cells.
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In animal cells, when do the cells lose their differentiated cells?
In early stages of life.
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In plant cells, when do they lose their differentiated cells?
They never do.
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Where do adult cells have stem cells? What's different about them?
Only in certain places, e.g. bone marrow. They can only differentiate in certain types of cells.
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What do doctors use to cure some diseases. Give an example.
They use adult stem cells, such as: sickle celled amaemia which is cured by bone marrow transplant.
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How do doctors get specialised stem cells?
By extracting stem cells from early human embryos and growing them in certain conditions so the differentiated cells can be specialised cells.
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What could stem cells be used to replace?
Damaged by diseases or injured cells.
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What are some ethical issues with stem cells?
1. Humans lives shouldn't be experimented with as this is potentially human lives. 2. Stem cells are banned in some countries or, have strict guide lines to follow - in UK. 3. Some say that curing ill patients is more important than embryos.
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Other cards in this set

Card 2


Give 7 things in a plant cell


Rigid cell wall, Large vacuole, Chloroplasts, Nucleus, Cytoplasm, Cell Membrane and Mitochondria

Card 3


What does the nucleus do?


Preview of the front of card 3

Card 4


What does the cytoplasm do?


Preview of the front of card 4

Card 5


What does the cell membrane do?


Preview of the front of card 5
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