B3 Living And Growing Flashcards
Where does respiration occur to provide energy for life processes
Mitochondria
What is the purpose of chromosomes and what it is made of?
- carry coded information in the form of genes
- made of a molecule called DNA
Define genetic code
Information in the genes in the form of coded instructions
Genetic code controls all cell activity and consequently some characteristics of the organism
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DNA controls the production of different proteins
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Proteins are needed for the growth and repair of cells
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Which scientists first discovered the structure of DNA
Watson and Crick
Explain why liver and muscles have large numbers of mitochondria
- liver cells need a lot of mitochondria as they require lots of energy as they carry out many reactions.
- muscles cells need a lot of mitochondria because they require a lot of ATP for contraction
Some structures in cells, such as ribosomes can’t be seen with a light microscope.
Ribosomes are in the cytoplasm and are the site of protein synthesis
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Describe the structure of DNA
Two strands coiled to form a double helix, each strand containing chemicals called bases, of which their are 4 different types, with cross links between the strands formed by pairs of base
Describe chromosome
Long coiled molecules of DNA, divided up into regions called genes
DNA has four bases : A, T, C, G. What are the complementary base pairings?
AT
CG
Explain how protein structure is determined by the DNA base code
- the base sequence determines amino acid sequence
- each amino acid is coded for by a sequence of 3 bases
Each gene:
- contains a different sequence of bases
- codes for a particular protein
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Where are proteins made and by why is a copy of the gene needed?
Proteins are made in the cytoplasm and a copy is needed because the gene itself cannot leave the nucleus
Explain how the code needed to produce a protein is carried from the DNA to the ribosomes by a a molecule called mRNA
The mRNA is a single-stranded molecule. It is a copy of one strand of a length of DNA.
Explain how DNA controls cell function by controlling the production of proteins, some which are enzymes
Enzymes control all the chemical reactions in your cells. So the genetic code controls the cell. As a consequence it controls most of your characteristics.
Describe how Watson and Crick used data from other scientists to build a model of the DNA
X-ray data showing that there were two chains wound in a helix
Data indicating that the bases occurred in pairs
Explain why new discoveries are not accepted or rewarded immediately
Other scientists have to repeat the work and verify it
It is not clear, straight away how important and useful the discovery is
The genes in a cell that are switched on determine the function of a cell
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Give some examples of proteins
Collage
Insulin
Haemoglobin
Describe enzymes
Enzymes are protein molecules that speed up a chemical reaction and work best at a particular temperature
Enzymes have active sites that the substrate molecules fit into when a reaction takes place
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Different cells and organisms will produce different proteins
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Describe gene mutations
Changes to genes
What are proteins made of?
Long chains of amino acids
Describe some functions of proteins
Structural-Collagen
Hormones-insulin
Carrier molecules-haemoglobin
Enzymes
How do proteins differ from each other
Each protein has its own number and sequence of amino acids, which results in differently shaped molecules which have different functions
Describe enzymes
Biological catalyst which catalyses chemical reactions occurring in the living cells (respiration, photosynthesis, protein synthesis) which have a high specificity for their substrate
What are anabolic and catabolic enzymes
Anabolic catalysts are used to build structures where as catabolic catalysts are used to break structure (Glucose breakdown)
Explain the specificity of enzymes in terms of the “lock and key” mechanism
Each enzyme is specific for its substrate molecule just like a key is specific for a lock
Describe the rate of reaction of an enzyme-catalysed reaction will change by increasing/decreasing temperature and changing the pH
By increasing the temperature, the rate of reaction will increase as the enzymes and substrates move more quickly and collide more often ( doubles after each 10’C). However after an extent, the enzymes denature. ( the shape of the active site changes, the substrate molecule can no longer fit in the active site, the rate of reaction decreases and eventually stops).
By lowering the temperature, there are lower collision rates, meaning the enzyme has become inactive.
If the pH is altered, the shape of the active site changes, meaning the substrate can’t fit in the active site, meaning the enzyme has denatured.
Gene mutations may lead to the production of different proteins.
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How can gene mutation occur?
- exposure to radiation or chemicals
- spontaneously
Only some full set of genes are used in any one cell; some genes are turned off
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Mutations can be useful, neutral or harmful
Useful : pale skins are caused by mutations, it would be useful for people who live in temperate regions of the world. It allows their skin to make vitamin D because the weaker sunlight can only penetrate through paler skin.
Harmful: cells to continue to divide (cancer), slightly differently shaped haemoglobin molecules (anaemia)
Neutral: being able to roll your tongue, free or attached earlobes
Explain how changes to genes alter or prevent the production of the protein which is usually made
Changes to gene involves the shape of an enzyme to change, meaning the enzyme can not longer catalyse the chemical reaction it used to do, now it can catalyse a new reaction due to the substrate not being able to fit in the new active site
The energy provided by respiration is needed for all life processes in plants and animals
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Word equation for aerobic respiration
Glucose + oxygen —> carbon dioxide + water
Describe examples of life processes that require energy from respiration
Muscle contraction
Protein synthesis
Control of body temperature in mammals
Explain why breathing and pulse rates increase during exercise
During exercise your muscle needs more oxygen per minute as it produces more carbon dioxide per minute.
The heart rate and pulse rate goes up to deliver more oxygen and glucose to your muscles per minute. Your breathing rate also goes up to remove the excess carbon dioxide quickly.
Symbol equation for aerobic respiration
C6H12O2 + 602 —-> 6CO2 + 6H2O + ATP
Oxygen consumption increases when Carbon Dioxide production increases
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Respiration results in the production of ATP and ATP is used as an energy source for many processes in the cell
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Explain how the rate of oxygen consumption can be used as an estimate of metabolic rate because aerobic respiration requires oxygen
As aerobic respiration requires oxygen, the amount of oxygen an organism uses in a particular period of time indicates its metabolic rate. The metabolic rate is a measure of how quickly all the chemical reactions are going on in the organism’s body.
Explain why the rate of respiration is influenced by the changes in temperature and pH
Not sure
Explain fatigue in terms of lactic acid being built up and how this is removed during recovery
Hard exercise causes lack of oxygen in cells
The incomplete breakdown of glucose
Continued panting replaces oxygen allowing aerobic respiration
Increased heart rate ensuring that blood carries lactic acid to the liver to be broken down
Explain why anaerobic respiration occurs during hard exercise in addition to aerobic respiration
When you start hard exercise, your heart does not go up quickly enough to provide the extra oxygen. To make up for the shortfall in energy release, your muscles cells use both types of respiration
Disadvantages of anaerobic respiration
Produces lactic acid
Accumulation of this can cause muscles pain and fatigue
Word equation of anaerobic respiration
Glucose —-> Lactic Acid + ATP