Biology paper 2

• Gametes


  Sex cells, sperm and egg. Chromosomes are single not paired. They are made by meiosis
• Fertilisation


  The fusion of the male and female gametes(sperm and egg). The genetic information gets mixed providing variation in the offspring
• Asexual reproduction


  Only one parent and produces genetically identical offspring (clones). No gametes involved so more energy and time efficient in favourable conditions. Increases the risk of exctitin
• Sexual reproduction


  1. Chromosomes are copied

  2. Cells divide to form 4 daughter cells

  3. Chromosomes are single

  4. Cells are fertilised

  5. The cell has chromosome pairs

  6. Mitosis occurs to form an embryo

  It provides variation and therfore provides a survival advantage
• Malaria reproduction


  In the human host malaria reproduces asexually. In a mosquito vector it reproduces sexually.
• Fungi reproduction


  Releases spores in air or water is asexually or can be sexually.
• Plant reproduction


  Sexually to produce seeds or asexually using runners or bulb division.
• DNA


  Determines our inherited structure and is found in chromosomes.

  
• Gene


  A small section of DNA on a chromosome. Encodes for a different amino acid and protein. The order of amino acids determines the shape and function.
• Human genome


  It is the entire genetic material that makes a human. Understanding it will allow us to search for certain genes linked to disease, understand inheritance and trace migration patterns.
• Protein synthisis


  How proteins are made. It has two parts transcription and translation.
• Transcription


  Happens in the nucleus. The base sequence is copied to a mRNA which leaves the nucleus
• Translation


  Happens in the cytoplasm. The mRNA attaches to a ribosome. tRNA brings amino acids which the ribosome puts together depending on the mRNA sequence. Chain folds up to form shape
• Mutation


  A change to the base sequence. Most of the time there is no effect, sometimes different amino acids are created so the genes doesn't do its fuction is is on when it shouldn't be
• Alleles


  Different versions of the same gene
• Genotype


  Tells us the alleles present in a person.

  Ee = heterozygous ee = homozygous.
• Phenotype


  Tells us the characteristics caused by the alleles. A dominant allele will show in the phenotype even if there is only one copy
• Cystic Fibrosis


  Disorder of the cell membranes. Recessive conditions meaning you need a homozygous small pair to get it e.g. cc
• Polydactyly


  Have extra fingers or toes. Dominant condititon meaning you only need one big allele to get such as in a heterozygous pair e.g. Pp
• Embryo Screening


  Embryos are tested for certain conditions and only normal embryos are imprinted. It is very expensive, many embryos are destroyed and may lead to screening for desired characteristics such as intelligence or beauty.
• Gender


  xy = male xx = female
• Variation


  All the differences in the characteristics of individuals in a population. It is caused by a combination of alleles, the environment and mutations.
• Evolution


  The change in the inherited characteristics of a population over time through the process of natural selection.
• Speciation


  When two groups have become so different that they cannot interbreed to create fertile offspring as a result of geographical isolation.
• Selective breeding


  There are 4 reasons to selectively breed:

  Gentle nature

  More meat/milk

  Larger fruits

  Disease resistance

  Select the two largest cows, breed them and repeat. May cause defects
• Genetic Engineering


  Identify the gene and isolate with enzymes.

  Transfer to a vector (plasmid or virus)

  Transfer gene into the desired organism at an early stage.

  It may be harmful to crops and it may damage the environment but it can be used to treat disaese
• Cuttings


  1. Remove a small growing part (meristem at shoot)

  2. Put it in rooting powder

  3. Replant it

  4. Grow the clone

  Been used for 100 years
• Tissue culturing


  1. Divide plant into tiny pieces (a few cells)

  2. Incubate cells with hormones

  3. Must be sterile

  It produces a lot of plants quickly and cheaply and can help to preserve rare species
• Embryo cloning


  1. Start with sperm and egg

  2. fertilise

  3. Allow to develop into an embryo

  4. Split the embryo

  5. Implant into surrogate mothers

  All of the offspring will be the same
• Adult cell cloning


  1. Take a body cell and remove the nucleus

  2. Take an egg cell and remove the nucleus

  3. Put the body cell nucleus in the egg cell

  3. Give the cell an electric shock so it splits

  4. Insert the embryo that forms into a womb
• Darwin


  Studied fossils and geology to discover evolution by natural selection (the more adapted animals are more likely to survive). 1859 origin of the species..

  People didn't agree because of strong religious beliefs, not enough evidence and no knowledge of genetics
• Lamark


  Thought giraffes stretched their neck and then it passed onto their offspring.
• Wallace


  Proposed the same theory as darwin
• Mendel


  Did experiments on pea plants and released features are not blended but passed on in units that can be masked.

  People didn't agree because there was no knowledge of genetics an he was an unknown scientist.
• Fossils


  Remains of organisms from millions of years ago which are found in rocks. They are formed when organisms don't decay, they are replaced by minerals or from footprints and roots.
• Extinction


  Happens as a result of

  - a catastrophic event

  - environmental changes

  - new diseases or predator

  - a more successful species
• Antibiotic resistance


  Random mutations make bacteria resistant to antibiotics. These bacteria survive and reproduce to form a resistant population. We should not over prescribe, restrict the use in farming and always complete treatments.
• Carl Linnaeus


  Developed a classification system.

  Kingdom

  Phylum

  Class

  Order

  Family

  Genus

  Species
• Carl Woese


  Developed three domain system.

  -Archaea (primitive bacteria)

  -True bacteria

  -Eukaryota
• Homeostasis


  The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes