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  1. interspecific variation
    differences within members of of the same species
  2. Aquired varitation
    differences caused due to your enviroment e.g tan, accents
  3. inhertied variation
    differences determined at the time of conception (traits your born with) there are two types of inherited variation, continuous and dis-continuous
  4. dic-continuous varration
    characteristics you have or dont
  5. continuous variation
    characteristics that can be put into a range of measurements. Everyone hads them but differs in measurement
  6. importance of variation
    • Some members of a population can develo[pe characteristics that enable them to survie and reproduce in the event of a disease outbreak or sudden climate change
    • Over time this leads to EVOLUTION
  7. Relationship between Cell neleus, chromosomes, DNA, genes, ana alleles
    • A pair of homologous chromosomes (one from each parent
    • Chromosomes are made of long DNA molecules shaped like a twisted ladder called a double helix
    • A section of DNA on a chromosome is called a gene
    • For each indiviual there is 2 genes or alleles found in the same place on the chromosome
    • the combo of 2 alleles is called a genotype
    • the characteristic shown is the phenotype
    • the characteristic is determined by our alleles
  8. Difference between Genes and Alleles
    A gene is a section of DNA which carries a unit of inheritance, which carries the gentic code for a particular trait, whereas an allele is one of a number of possible forms of a gene e.g a gene is eye colour and blue/brown/green/black/hazel are different alleles
  9. Asexual reproduction advantages
    Simple and rapid. Many offspring produced rapidly
  10. asexual reproduction disavantages
    They are genetically identical, so species can be completely wiped out in the event of a disease outbreak or sudden climate change
  11. Sexual Reproduction avantages
    Produces variation so can handle a disease outbreak or sudden climate change
  12. Sexual Reproduction disavantages
    Long and unpridictable, and only produces a few offspring
  13. Mitosis
    • Is a process responsable for growth of an orgainsim, repair and replacement of damaged or old tissues
    • During mitosis two identical offspring are produce from a single mother cell
    • It involves DNA replication where and exact copy of the DNA is made
    • Every living being under goes mitosis
    • Mitiosis takes place in all body cells except the cells of the gonads
  14. Mitosis Interphase
    Some chromosomes shorten and fatten and become visible
  15. Mitosis Prophase
    Chromosomes replicate and the membrane around nucleus disappers. The chromosomes are still joined by the centrome at this stage
  16. Mitosis
    Chromosomes line up along the middle of the cell
  17. Mitosis Anaphase
    Chromosomes separate, going to opposite end sof the cell
  18. Mitosis Telophase
    The parent cells split ( when the cell pinchs in is called Cytokinesis, separting to cytoplasm) The daughter cell is formed and is diploid
  19. Diploid
    when the nucleus gets the same number of chromosomes as its orginal cell
  20. Haploid
    a cell with half the number of chromosomes as its orginal cell
  21. Meiosis
    Purpose is to create new gametes that are gentically different, which creates variation within a sepecies. I also ensure the no. of chromosomes remain comstant
  22. Meiosis
    • 1. Homologous chromosomes pair up
    • 2.chromosome replicate
    • 3.Homologous replicated chromosomes come together and the chromosomes cross over. Each chromosome now carries different genes to what it started with
    • 4.two new cells form with a mix of chromosomes
    • 5. chromosomes separate and go to different ends of the cell. Which chromosome goes where is totally random
    • 6. four unique gamets are formed which are haploidn and have different chromosomes
  23. Monohybrid crossing
    crossing for only one charateristic. The simple pattern produced by the crossing of only one characteristic or trait given by one pair of alleles
  24. Role of DNA
    It is reposible for making up proteins in a cell. organisms are unique because of the different make up of the protiens in there cells
  25. DNA Structure
    DNA forms a shape called a double helix, which is like a twisty ladder. It is made of Phosphate molecules, deoxyribose sugars, and bases, held together with hydrogen bonds. the bases pair up ti make base pairs, and only pair with certain bases (thymine and adenine, cytosine and guanine). One sugar one phosphate and one base creates a nucleotide. And three nucleotides make a codon. A squence of three bases is a triplet. One codon creates one amino acid
  26. Starting of a gene
    every gene start it sequence with ATG
  27. DNA replication
    • DNA replication is a semi-conservative process
    • It starts with the DNA molecule untwisting
    • then the hygroden bonds holding the base pairs together break causing the molecule to 'unzip'
    • So the bases are no longer paired
    • New strands are then made by free nucleotide moving and combining with the complimentary pairs.
    • These new strands are formed against the orginals
    • Once the new strands are formed, the two new strands twist and 'zip up' to form two new DNA strands
  28. Genetic code
    is a sequence of bases/triplets/codons in the DNA molecule that codes for a particular trait of and orgainsim
  29. Mutations
    Is a perminate change in the DNA sequence caused by an error that may occur with base pairing durning DNA replication. This causes a change in the genetic codes, and can alter the amino acids being produced
  30. Mutations; Why
    They may be random or triggered by exposure to environmental factors such as excess radiation from the sun or nuclear reactions or explosions of carcinogenic chemicals like nicotine or tar in tobacco or some organic solvents
  31. Sex Determination
    the sex of an offspring is determined by the sex chromosomes which are the 23rd pair of chromosomes. Males have X and Y sex chromosomes and females have just X ( so X and X) X is the bigger of the two chromosomes. Becasue females can only give X chromosome the gender of the offspring depends on the sex chromosome in male gamete. There is a 50:50 chance of having a boy or girl
  32. Cloning process
    • A body cell is taken
    • It is made to divide mitiotically to form a row of cells
    • one of these is put next to and egg cell which the nucleus has been removed
    • the two cells are made to fuse through electric current to form a diploid cell
    • the cell is them made to grow normally as a zygotr to form a new organism
  33. Test Crossing
    • Test crossing is a method to find out weather one of the parent is homozygous or heterzygous for a characteristic. One must cross that with a pure breed homozygous recessive
    • (NOTE: if I write about test crossing, draw 2 punnett diagrams, one BB and Bb)
  34. Inherting mutation
    If mutation takes place during the formation of a gamete it id inhertited. If it takes place int the body cell then it will not be
  35. Changes in mutation
    can be caused either due to insertion or deletion of a base, or swaping of a base with an other
Card Set:
2011-10-21 09:43:14
Science biology

other bio stuff
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