Biology Revision

• What is Genetics?


  The science of genes and how traits are passed from one generation to the next.
• What are genes?


  Sections of DNA that code for the production of protein.
• Where can DNA be housed?

  In the nucleus, mitochondria and chloroplasts (plants).
• What are the barriers protecting animal cells?

  Nuclear membrane - membrane that surrounds the nucleus.

  Cell/plasma membrane - membrane that surrounds the whole cell.

  Both are made up of a lipid (fatty/oily) material.
• What are the barriers protecting plant cells?

  Nuclear membrane - membrane that surrounds the nucleus.

  Cell/plasma membrane - membrane that surrounds the whole cell.

  Cell wall - A tough substance called cellulose that surrounds cell membrane.
• What are Chromatin?


  All of the linear strands of DNA that are partly coiled up during most of a cells life.
• What are chromosomes?


  Multiple linear strands of DNA that have condensed and coiled tighter together as the cell divides.
• What does DNA stand for?

  DeoxyriboNucleic Acid
• What is a nucleotide?


  The building block of DNA; a repeating pattern of 3 (deoxyribose sugar, phosphate group and nitrogenous base) that makes up DNA.
• What is the bond that connects nitrogenous bases?

  Hydrogen bonds (weak)
• What are the 4 types of nitrogenous bases?

  Thymine, Adenine, Guanine, Cytosine
• What is the base-pairing rule?

  Only complimentary bases can pair together (A <-> T) (G <-> C)
• What is the 5 carbon sugar in a nucleotide and what is its charge?

  deoxyribose/ribose sugar (neutral/no charge)
• What is the overall charge of a phosphate group?

  Negative, because of the two oxygen atoms.
• What is DNA replication?

  The process by which an organisms DNA is copied. It is semi-conservative (half old and half new). This happens before mitosis/meiosis (during the S phase in interphase).
• What are the 4 enzymes involved in cell devision and what are their roles?

  DNA helicase - unzips the DNA strand

  DNA primase - Puts primers (shorts strands of RNA) that bind to the DNA

  DNA polymerase - attaches to the primers and fills in the blank bits (with nucleotides).

  DNA ligase - bonds the nucleotides together.
• What is cell replication and what is it needed for?

  Cell replication is how cells produce new cells. We need it for growth, repairing and replacing damaged cells, and the production of sex cells.
• What are somatic cells?

  A body cell that has 46 strands (23 pairs) of DNA. Because they have 2 copies, we call them DIPLOID. We inherit one copy from each of our parents.
• What are gametes?


  Gametes are sex cells. We call the HAPLOID because they only contain one copy of DNA in their nuclei.
• What is a zygote?


  A zygote is a diploid sex cell that occurs when 2 haploid cells (one sperm and one egg) combine to create a fertilized egg.
• What is cell division?


  The process by which cells reproduce (either mitosis or meiosis).
• What is mitosis?


  Mitosis is body cell devision. It is when a single cell divides once into 2 identical 'daughter' cells.
• What is meiosis?


  Meiosis is reproductive cell division. It is known as reductional cell division because the 2 cells have half as many as their parent cell, they also go through 2 divisions and produce 4 cells. They are NOT identical.
• What is the difference between mitosis and meiosis?

  Mitosis is used for growth and repair, while meiosis is used for the production of sex cells. Mitosis produces 2 genetically identical daughter cells, while meiosis produces 4 genetically varied daughter cells.
• What are the steps in mitosis?

  Interphase (normal functions + preparing for cell division), Prophase (nucleoli disappears, nuclear membrane breaks down, centrioles move to opposite poles and spindles form), Metaphase (Chromosomes line up in the middle of the cell and attach to individual spindles), Anaphase (centromeres divide and move 1/2 a chromosome to their side), Telophase (spindles disappear, and nuclear membrane and nucleoli form, centrioles divide and chromosomes uncoil) and Cytokinesis (cytoplasm divides into 2). -- I-P-M-A-T
• What is the cell cycle?


  The sequence of events leading up to and during cell division. The 2 main parts are interphase and the mitotic phase.
• What are the steps of meiosis?

  Interphase (normal functions + preparing for cell division), Prophase (nucleoli disappears, nuclear membrane breaks down, centrioles move to opposite poles and spindles form), Metaphase (Chromosomes line up in the middle of the cell and attach to individual spindles), Anaphase (centromeres divide and move 1/2 a chromosome to their side), Telophase (spindles disappear, and nuclear membrane and nucleoli form, centrioles divide and chromosomes uncoil) and Cytokinesis (cytoplasm divides into 2) and repeat. -- I-P-M-A-T - P-M-A-T-C
• What is an allele?


  An alternate version of a gene.
• What is a genotype?


  The genes present in the DNA of an individual.
• What is a phenotype?


  The observable characteristics of an individual, determined by the genotype.
• What is a punnett square?


  A diagram used to predict the possible genetic outcomes of a breeding. (monohybrid = 2 alleles for 1 gene)
• What is a pedigree chart?

  A chart used to track and examine inheritance within a family.
• What is an autosomal allele?

  A non sex related allele/gene.
• What is an sex-linked allele?


  An allele/gene related to the sex chromosome.
• Why are heterozygotes called carriers?

  Because they carry a recessive allele.
• What are the 2 steps to interpreting a pedigree chart?

  1. determine whether it is autosomal or sex linked

  2. determine wether it is dominant or recessive
• What is biodiversity?


  The variation of life in our biosphere (an area on earth inhabited by living things, i.e. land, water, air).
• _____ is the term given to one species existing in a place at a given time.

  POPULATION is the term given to many species existing in a place at a given time.
• _____ is the term given to many species existing in a place at a given time.

  COMMUNITY is the term given to many species existing in a place at a given time.
• What is a gene pool?

  All of a populations' genes and alleles.