6.sex cells and fertilisation
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6.sex cells and fertilisation






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6.sex cells and fertilisation 6.sex cells and fertilisation Presentation Transcript

  • Sex Cells and Fertilisation Sexual Reproduction
  • Sexual Reproduction
    • Copy the following definition:
    • Reproduction is the method by which the members of a species produce offspring. Sexual reproduction involves the fusion of two gametes (sex cells) during fertilisation .
  • Sexual Reproduction (plant) Petals Anther Filament Nectary Sepal Ovule Style Stigma Ovary Stamen }
  • Sexual Reproduction (plant) Pollen Tube
  • Sexual Reproduction (mammal) Nucleus – contains information in chromosomes Cytoplasm – contains food store Head Tail – allows sperm to swim to egg
  • Sexual Reproduction (mammal) Fertilisation is when the two nuclei fuse
  • Sexual Reproduction
    • Note:
    • Fusion of nuclei forms a zygote containing genetic material from both parents.
  • Sexual Reproduction Notes
    • Answer Tp163-164 ‘Testing Your Knowledge’ in sentences .
    • Collect cut-outs and
      • label the parts
      • draw an ‘X’ where fertilisation occurs
    • Extension work – Success Guide p36-37
  • Sex Cells and Fertilisation Genetics
  • Genetics Notes
    • Copy the definition below:
    • Chromosomes are thread-like structures found inside the nucleus of every living cell. They contain genetic information which gives rise to an organisms characteristics.
  • Genetics The number of chromosomes present in an organisms’ cells depends on its species. e.g Human Male 46 Chromosomes
  • Genetics The thread-like chromosomes are made of a chemical substance called DNA. DNA carries coded genetic information. DNA has two strands which form a twisted structure called a helix. Each piece of information is called a gene.
  • Genetics Notes
    • Copy the definition below:
    • A gene is a section of a chromosome which contains a separate piece of genetic information.
  • Genetics
    • Rows of four different
    • bases make up a strand of DNA.
    • The order of the bases
    • makes the DNA code.
    A A C T G C C G T A T G Adenine (A) Thymine (T) Guanine (G) Cytosine (C)
  • Genetics A A C T G C C G T A T G The genetic code found in genes gives the cells instructions to make protein molecules.
    • The proteins produced have a variety of jobs e.g.
    • structural (muscle tissue),
    • controlling cell activities (enzymes)
  • Genetics Notes
    • Answer Tp167 Q2 in sentences .
    • Label the cut-out and stick it in.
  • Genetics
    • Protein molecules are made from combinations of 20 available amino acids , linked together in a long chain.
    • The DNA molecule tells the cells which amino acids to use when making a specific protein .
  • Genetics
    • Three bases (e.g. ATG) carry the code for one
    • amino acid.
    Each amino acid is different depending on the combination of bases (e.g. CGT, TGC, AAG etc) Amino acid Amino acid Amino acid Amino acid
  • Genetics The amino acids are linked together to make a protein. The sequence of amino acids dictates the structure and function of the protein. Amino acid Amino acid Amino acid Amino acid Protein molecule
  • Genetics Notes
    • Complete the cut-out and stick it in.
    • Answer Tp167 Q3 .
    • Use the passage ‘Proteins’ on Tp165 to make a note about the relationship between proteins present in a cell and an organism’s characteristics.
    • Extension work: Success Guide p38-39.
  • Fertilisation Mini Essay Describe how and where fertilisation occurs in a flowering plant. For Wednesday 15 th December
  • Sex Cells and Fertilisation Gamete Production
  • Gamete Production Notes
    • Note :
    • Body cells have two matching sets of chromosomes. Gametes have one set of chromosomes.
    • The reduction in number of chromosomes to a single set occurs during meiosis (gamete formation).
  • Gamete Production Chromosome Chromatid Chromatid Centromere Centromere Centromere
  • Gamete Production Notes
    • Copy these definitions:
    • A chromatid is the name given to each single strand of a double chromosome
    • A centromere is part of a single chromosome. In double chromosomes, it holds the two chromatids together.
  • 4 gametes produced. Gamete Mother cell. 4 double chromosomes. Matching chromosomes pair. Line up across cell Pairs separate. Cell divides. Chromosomes line up. Each cell divides again. Centromeres split Chromatids pulled apart
  • Gamete Production Notes
    • Answer Tp173 Q2+3 in sentences .
  • Sperm Mother cell Egg Mother cell Cell ready to divide again Sperm cell Egg cell MEIOSIS Zygote FERTILISATION
  • Sex Cells and Fertilisation Sex Determination
  • Sex Determination Notes
    • Every normal body cell in a human being contains 46 chromosomes as 23 pairs.
    • Of these, one pair makes up the sex chromosomes.
    • Females have two large X chromosomes, while males have a large X and a small Y chromosome.
  • Sex Determination Notes
    • Complete and stick in the sex chromosomes cut-out.
  • Gamete Production
    • Note :
    • In humans, each male gamete has an X or a Y chromosome, while each female gamete has an X chromosome.
    • Now fill in the sex determination grid to work out the expected ratio of boys:girls.
  • Gamete Production
    • Look at Tp175 Q5 (you don’t need to write anything down – just think about the question.)
  • Sex Cells and Fertilisation Genes and Alleles
  • Genes and Alleles Note
    • Chromosomes are made up of smaller units called genes . Each gene is a unit of heredity that controls an inherited characteristic (e.g. wing type, hair texture, flower colour, etc.)
  • Genes and Alleles Note
    • Alleles are different forms of a particular gene. At least two forms of each gene normally exist among the members of a species. For example in pea plants, the gene controlling flower colour can produce lilac or white coloured flowers.
    • The alleles of a gene are found at the same location on each member of a pair of chromosomes.
  • Genes and Alleles Note
    • Using the green booklets, make notes on 6.7 section 2 only (The Segregation of Alleles)
    • Read through 6.7 section 3
    • Finally, attempt the check test for 6.7.