B3 Flashcards
What is DNA
DNA is two strands coiled together to form a double helix. Each of the strands contains chemicals called bases and there are for different types. There are cross links between the strands to for pairs of bases..
Each gene has coded…..
genetic information
What are chromosomes?
They are long, coiled up molecules of DNA - they are divided into sections called genes
What do genes contain? What do they code for?
The genetic code consist of different sequences of base pairs in a particular length of DNA. Each gene codes for a particular protein
Where are the proteins made and why is a copy of the gene needed?
The Proteins are made in the cytoplasm. A copy of the gene is needed as the gene cannot leave the nucleus; they are in chromosomes
What are the four bases of DNA?
A, T, G, C
Describe complementary base pairing
A always pairs with T, and G always pairs with C
How does protein structure determine the DNA base code?
The base sequence determines the amino acids and each amino acid is coded by a sequence of base triplets
How does the code needed to produce a protein carried?
The code is carried from the DNA to the ribosomes by a molecule called mRNA
How does DNA control cell functions?
It control the production of proteins, some of these are enzymes.
How did Watson and Crick use data from other scientists to build the model of DNA?
W and C used x-ray data showing there were two chains wound in a helix. They also obtained data indicating the bases occurred in pairs.
Why are new discoveries not accepted or rewarded immediately?
They need to be repeated and tested by other scientists to test the work; they need verify it
What are proteins made of?
They are made from long chains of amino acids
What is collagen?
Collagen - structural protein makes up structure of body.
What is an enzyme?
They are biological catalysts as they catalyse chemical reactions occurring in living cells e.g respiration, photosynthesis, protein synthesis. They also have high specificity in for the substrate molecule
Describe the lock and key mechanism
The substrate molecule fits into the active site. This is called specificity as the substrate has to be the right shape, like a key
What will change the rate of the reaction in an enzyme catalysed reaction?
pH and temperature change away from optimum
How is enzyme activity affected by temperature and pH?
Low temperatures mean lower collision rates
Extremely high pH and temperature means enzymes denature
Denaturing is irreversible and damages enzymes (active site)
What is temperature coefficient? (Q10)
Rate at higher temperature / rate a lower temperature
What is insulin?
Hormone made in pancreas. Traces in blood stem to target irfan. It regulates blood sugar level.
What is haemoglobin?
In red blood cells. Carries octane from lungs to resourcing cells. Carrier protein.
What can gene mutations lead to?
Occurs spontaneously. And can cause production of different proteins.
How do mutations occur?
Spontaneously but can occur more with radiation and chemicals
What are the three possibilities of mutations?
They can be harmful, beneficial or have no effect
How many genes are used in any one cell?
Only some ill sets are used as some are switched off.
What types of genes determined the functions of a cell?
Genes that are switched on
How do changes to genes alter the production of protein that is normally made?
Changes to gene changes base code of DNA which changes order of amino acid in proteins
What is the symbolic equation of aerobic respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O
What happens as the rate of respiration increases?
The rate of respiration increase means the oxygen consumption increases. More carbon dioxide is produces.
What is the respiratory quotient (RQ)?
Carbon dioxide produced/oxygen produced
What does the respiration produce, and what is the product used for?
ATP is produced and this is the main energy source for many processes in cells
What can the rate of oxygen be used for?
It can be used to estimate the metabolic rate because aerobic respiration requires oxygen.
How is the rate of respiration influenced by changes in temperatures and pH?
This happens because of enzyme activity and respiration is controlled by enzymes.
Why does anaerobic respiration take place during hard exercise?
As muscles need to receive sufficiently gem supply.
What does anaerobic reputation produce and what does it cause?
It produces lactic acid, and pain and fatigue as it accumulates in the muscle.
What is the more equation for anaerobic respiration?
Glucose -> lactic acid
What is a disadvantage of anaerobic respiration?
It released less energy per glucose molecule than aerobic respiration
What are the advantages of being multicellular?
It allows organisms to be larger. It allows cell differentiation and it allows the organisms to be more complex.
What does mitosis produce?
It produces new cells for growth.
Why are new cells of mitosis genetically
The new cells are genetically identical as DNA replication has taken place; each cell produced has two copies of each chromosome.
In mammals, body cells are…
Diploid - they have two copies of each chromosome
Why must DNA replication take place before cells divide?
So that each of the cells produced haas two copied of the same chromosome
How does DNA replication happen (before mitosis)?
Two strands of the DNA molecule unzips to form single strands . New double strands are formed by complementary base pairing
What happens in mitosis?
The chromosomes line up along the centre od the cell. They then divide. The copies move to the opposite poles of the cells.
What does meiosis produce?
Gametes
What are gametes
They are haploid; they contain one set of chromosomes in each pair
How does fertilisation result in genetic variation?
The games combine to form a diploid zygote. The games on the chromosomes combine to control the characteristic of the zygote.
How if the sperm cell adapted for its functions?
it has many mitochondria to provide energy. It has an acrosome that releases enzymes to digest the egg membrane
How are the structure of the red blood cells adapted to their functions?
They are very small meaning they can pass through the smallest blood vessels. They are shaped like a biconcave disk so they have a large surface area to exchange oxygen quicker. They lack nucleus so more haemoglobin can fit in.
How is the red blood cells are adapted to their functions
It is shaped like a biconcave disc, providing it with a large surface area to volume ratio
What does haemoglobin react with to form oxy haemoglobin and how is this reaction irreversible?
The haemoglobin in the red blood cells react with oxygen on the lungs to form oxyhaemoglobin. The reaction is irreversible as when this reaches the tissue, the oxygen is released.
