Biology 2b

Biology 2b

Enzymes
1. Enzymes are catalysts produced by living things.
2. Enzymes are produced in living things to act as a catalyst.
3. A catalyst is a substance which increases the speed of a reaction, without being changed or used up.
4. They have special shapes so they can catalyse reactions. The shape of the enzyme fits onto the substance in the reaction.
5. Each enzyme usually only catalyses one reaction.
6. They need the right temperature and PH.
  1. Enzymes in the human body normally work best at around 37*.
Enzymes and Digestion
1. Digestive enzymes break down bug molecules into smaller ones.
  1. Types: STARCH PROTEINS FATS sugars amino acids glycerol fatty acids.
2. Amylase - converts starch to sugars. It is made in three places: pancreas, salivary glands and small intestine.
3. Protease - converts proteins to amino acids. It is made in three places: stomach (its call pepsin in there) pancreas and small intestine.
4. Lipase - converts lipids (fats and oils) into glycerol and fatty acids. It is made in two places: pancreas and small intestine.
5. Bile neutralises the stomach acid and emulsifies fats.
  1. produced in liver, stored in gall bladder then into small intestine. It emulsifies fats into small droplets making digestion faster.
Enzymes and Respiraton
1. Respiration is the process of releasing energy from glucose which goes on in every cell.
2. Aerobic Respiration needs oxygen, usually happens in the mitochondria.
  1. glucose + Oxygen --> Carbon Dioxide + Water + Energy
3. Respiration gives energy for: building up larger molecules from smaller ones, to allow the muscles to contract in animals, to keep body temp in birds and mammals and in plants to build sugars, nitrates and other nutrients into amino acids which are then built up to proteins.
Exercise
1. Glycogen is used during exercise.
2. Anaerobic respiration is used if there's not enough oxygen.
  1. Glucose --> Energy + Lactic Acid
  2. Not good as lactic acids builds up in muscles and is painful.
  3. Leads to oxygen debt.
    1. Aka heavy breathing.
Uses of Enzymes
1. Biological detergents - Washing powder as they break down animal and plant matter.
2. Food - Pre-digesting baby food using proteases, carbohydrases turn starch syrup into sugar syrup they are also used to sweeten slimming food products.
3. Industry - To speed up reactions without the need of high temperatures.
  1. Advantages - Specific so they only catalyse if you want them to, lower cost, use more than once and less environmental pollution as they are biodegradable.
  2. Disadvantages - allergies eg me with washing powder, easily denatured therefore highly controlled, expensive to produce and easily contaminated.
DNA
1. Chromosomes are long molecules of DNA.
2. Contains instructions to put an organism together and make it work.
3. Found in the nucleus of animal and plant cells.
4. A gene is code for a specific protein, made by stringing 20 amino acids together in an order.
5. Finger print DNA is used in forensic science and paternity testing.
Stem Cells
1. Sometimes cells can be specialised, in plants the cells can specialise at any stage.
2. Stem cells in a human can be found in places like bone marrow.
3. Diseases
  1. Adult stem cells are used, for example, with people that have a blood disease, stem cells found in bone barrow are used to treat this via transplant. This works because the stem cells can turn into new blood cells.
4. They can also be extracted at the very early stages of a human embryo.
5. To change the stem cell they are grown in specific enviroments, however there is much more research needed.
6. Arguments Against Stem Cell Research
  1. Embryos are potential human life.
    1. However, people argue that the life that is in need of the stem cell is more important.
X and Y Chromosomes
1. Male: XY Female: XX
2. Genetic Diagrams
  1. You can use genetic diagrams to look at the probability of the sex. However, there are other things genetic diagrams can show us, our characteristics.
  2. Alleles are different versions of the same gene.
    1. If an organism has two alleles that are the same this is (homo)zygous, if the two alleles are different this is called (hetero)zygous.
    2. If they are homozygous that is the gene, if they are heterozygous the dominant allele is the gene.
    3. Genotype = what alleles you have.
    4. Phenotype = the actual characteristic.
The Work of Mendel
1. Looked at peas and saw that the type varied and that this was not a coincidence.
2. His conclusions: 1) Characteristics in plants are determined by hereditary units. 2) Hereditary units are passed on from both parents, one from each. 3) Hereditary units can be dominant or recessive.
Genetic Disorders
1. For a child to have a disorder both parents must either be carriers or suffers.
2. Embryo Screening is where you are able to remove a faulty cell during IVF to avoid genetic disorders.
  1. For ES: Stop suffering, laws are in place to stop it getting out of hand, during IVF most embryos are destroyed anyway and treating the disorders costs tax payers money.
  2. Against ES: People may want to treat is as build a bear, rejected embryos are destroyed, implies that disorders are 'undesirable' and screening is expensive.
Fossils
1. The remains of plants and animals.
2. 1) Gradual replacement by minerals, things that take long to decay eg teeth are eventually replaced by minerals as they decay, forming a rock-like substance shaped like the original part.
3. 2) Casts and impressions, organisms buried in a soft material like clay leave a cast of itself as the material hardens.
4. 3) Preservation in places where no decay happens, in amber and tar pits there's no oxygen or moisture so decay microbes can't survive.
Extinction and Speciation
1. Extinction
  1. The dying out of a species.
  2. If you can't evolve quick enough, the environment changes too fast, a new predator kills them all, or a new disease, can't compete for food, a catastrophic event kills them all or a new species develops.
2. Speciation
  1. The development of a new species.
  2. This happens when populations of the same species become so different they cannot breed.
  3. 1) The same species in different packs 2) Packs separated by physical barrier 3)populations adapt to new environment 4) Development of a new species
Cell Divsion
1. Mitosis
  1. Used when plants and animals want to grow or to replace cells that have been damaged.
  2. 1) In a cell that's not diving, the DNA is all spread out in long strings.
  3. 2) if the cell gets a signal to divide it needs to duplicate DNA.
  4. 3) The chromosomes then line up at the centre of the cell and cell fibres pull them apart. The two arms of each chromosomes go to opposite ends of the cell.
  5. 4) Membranes form around each of the sets of chromosomes. These become the nuclei of the two new cells.
  6. 5) The cytoplasm divides, you now have two new cells containing exactly the same DNA - They're identical.
  7. Asexual reproduction also uses mitosis.
2. Meiosis
  1. Sex cells only have half the required number of chromosomes.
  2. It involves two divisions.
  3. 1) Before the cell starts to divide, it duplicates its DNA.
  4. 2) In the first division the chromosome pairs line up in the centre of the cell.
  5. 3) The pairs are then pulled apart, so each new cell only has one copy of each chromosome.
  6. 4) In the second division, the chromosomes line up and the two arms of each chromosome go to opposite ends of the cell.
  7. 5) The two cells then split up to form four gametes with only a single set of chromosomes in it.

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