B3.1 Flashcards
Name the parts of an animal cell. (5)
Nucleus Cell Membrane Cytoplasm Ribosomes Mitochondria
Name the parts of a plant cell (7)
Nucleus Cell Membrane Cytoplasm Ribosomes Mitochondria Chloroplasts Vacuole
What is the role of a nucleus?
- It coordinates the cells activity.
2. It contains the DNA
What is the role of a cell membrane?
Controls the movements of substances inside and out
What is the role of a cytoplasm?
- It helps keep the cell in place
2. It contains molecules such as enzymes which are responsible for breaking down waste
What is the role of a ribosome?
It is where protein is stored
What is the role of Mitochondria?
Where respiration takes place
Where is the mitochondria?
Cytoplasm
What does the number of mitochondria in the cytoplasm depend on?
The activity in the cell.
Why do cells such as liver cells and muscle cells have a lot of mitochondria?
The liver carries out many functions and muscle cells needs to contract. This requires a lot of energy.
Where are the ribosomes?
They are also found in the cytoplasm
What is smaller a ribosome or mitochondria?
Ribosomes. They are too small to be seen with a light microscope and are the site of protein synthesis.
Each genes in the nucleus contain..
- A section of a chromosone made of DNA
2. A code for a particular protein
How would you describe DNA?
- It is made up of two strands coiled to make a double helix.
- Each of those coiled strands contain chemicals called bases.
- There are 4 of these bases.
- The four bases are called A, T, C and G. The cross links holding the two strands together are always between the same bases, A-T and G-C. This is called complementary base pairing.
How do codes leave the nucleus if DNA can’t?
A copy of the gene has to be made so that it can leave the nucleus and carry the code to the cytoplasm.
What controls which protein is made?
The DNA base code
How does the DNA base code control which protein is made?
The base sequence in the DNA codes for the amino acid sequence in the protein. Each amino acid is coded for by a sequence of three bases.
How is the code carried from the DNA to the ribosomes?
By a molecule called Messenger RNA
Most of the proteins are made into?
Enzymes which control the activity of the cell
What did Watson and Crick find out?
Using the data from other scientists they:
- Took photographs using x-rays which showed that DNA had two chains wound in a helix
- Found data that the bases occurred in pairs
When did Watson and Crick work out the structure of DNA?
When did they receive the Nobel Peace Prize?
They worked out the structure of DNA in 1953
They won the Nobel Peace Prize in 1962 because they needed proof from other scientists.
What are proteins made up of?
Amino acids joined together
Name the functions of proteins
- Structural proteins used to build cells and tissues, e.g. collagen
- Hormones which carry messages to control a reaction, e.g. insulin.
- Carrier proteins, e.g. haemoglobin (carries oxygen)
- Enzymes
What makes each type of protein molecule have a different shape and a different function?
The number and order of amino acids.
What are biological catalysts?
Another word for enzymes because they speed up reactions in the body
Which reactions do enzymes speed up?
respiration, photosynthesis and protein synthesis of living cells.
How do enzymes speed up reactions?
The substrate molecule fits into the enzyme like a key fitting a lock
Why can’t any enzyme work in a particular substrate?
Because of specificity and the substrate and the active site of the enzyme have to “lock”
What is “the optimum”
This is when enzymes all work best at a particular temperature and pH. Any change away from the optimum and the reaction will slow down
How does temperature and pH slow down the rate of reaction?
- It is less likely for more collision to take place at lower temperatures
- At extremely high temperatures and pH denaturing occurs
What is the formula of calculating how temperature changes the rate of reaction
Q10 = Rate at higher temperature
_____________________
Rate at lower temperature
(Q10= temperature coefficient. This is done for a 10 degrees Celsius change in temperature)
How do mutations occur?
Either by radiation or chemicals
What happens when mutations occur?
Production of different proteins
How comes every cell in the body has the same genes but not all the same proteins are made?
Different genes are switched off in different cells. This allows different cells to perform different functions
What do gene mutation cause?
They may change or prevent the production of protein normally made, this changes the order of amino acids in the protein
What is respiration?
Releasing energy
Why is respiration important?
Energy is released from food and this energy is trapped in a molecule called ATP. ATP can then be used for many different processes in living organisms.
What is aerobic respiration?
Producing energy using oxygen
What is the symbol equation for aerobic respiration?
C6 H12 6O2 -> 6H20
What is anaerobic respiration?
A form of respiration using electron acceptors other than oxygen
What is the word equation for anaerobic respiration?
Glucose -> lactic acid + energy
What are the disadvantages of anaerobic respiration?
- Lactic acid that is made by anaerobic respiration causes pain in the muscles
- Anaerobic respiration releases much less energy per glucose molecule than aerobic respiration
What is oxygen debt?
The incomplete breakdown of glucose resulting in the build up of lactic acid
Why during recovery does the breathing rate and heart rate stay high?
- Rapid blood flow can carry lactic acid away to the liver
2. Extra oxygen can be supplied, enabling the liver to break down the lactic acid
What are the two ways you can measure the rate of respiration?
- The rate at which carbon dioxide is made
2. Measuring how much oxygen is used up (the faster it is consumed, the faster the respiration rate)
What is the respiratory qoutient?
The ratio of the volume of carbon dioxide evolved to that of oxygen consumed by an organism, tissue, or cell in a given time.
What is the formula to calculate the respiratory quotient?
RQ = carbon dioxide produced
_________________
oxygen used
How do changes in temperature and pH change the rate of respiration?
They affect enzymes and respiration is controlled by enzymes
What is the metabolic rate described as?
The sum of all reactions that are occurring in the body. Metabolic rate is high = more oxygen needed = aerobic respiration faster
What are the advantages of the multicellular?
Allows an organism to become larger and more complex. It also allows different cells to take on different jobs. This is called cell differentiation
What does every multicellular organism need?
- Communication between all cells in the body.
- Supply all cells with a enough nutrients
- Control exchange with the environment such as heat and gases
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What is the first step of mitosis?
The DNA replicates. This is done by unzipping the double helix structure.
What is the second step of mitosis?
The chromosome divides to form double armed chromosomes which line up at the centre of the cell.
What is the third step of mitosis?
Cell fibres pull these double armed chromosomes to opposite poles of the cell. Membranes from around the poles.
What is the fourth (last) step of mitosis?
Two genetically identical cells (daughter cells) are formed
What is mitosis?
A process that produces new cells for growth and repair
What is meiosis?
A type of cell division that produces gametes
What type of cell is a gamete?
A haploid cell (contains only one copy of each chromosome)
How comes the zygote is a diploid cell if both gamete cells are haploid?
The zygote gets one copy of a gene from one parent and another copy from the other parent. This causes genetic variation
How is the sperm adapted to its function?
- It has many mitochondria to provide the energy for swimming to the egg
- It has an acrosome that releases enzymes to digest the egg membrane
What is the first step of meiosis?
In the diploid cells, the single strands are copied to make x-shaped chromosomes
What is the second step of meiosis?
The new chromosomes pair up
What is the third step of meiosis?
One chromosome from each pair move to opposite poles of the cell
What is the fourth step of meiosis?
The strands of each (4) chromosome are pulled apart to opposite poles of the cell
What is the fifth (last) step of meiosis?
Four new haploid cells form, genetically different from each other
How many times in total does the cell divide?
2.
Fist division = one chromosome from each pair moves to opposite poles of the cell.
Second division = the copies of each chromosome come apart and move to opposite poles of the cell
