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Sex Cells and Fertilisation

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Presentation on theme: "Sex Cells and Fertilisation"— Presentation transcript:

1 Sex Cells and Fertilisation
Sexual Reproduction

2 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.

3 Sexual Reproduction (plant)
Petals Stigma Anther } Stamen Style Filament Ovule Ovary Nectary Sepal

4 Sexual Reproduction (plant)
Pollen Tube

5 Sexual Reproduction (mammal)
Cytoplasm – contains food store Head Tail – allows sperm to swim to egg Nucleus – contains information in chromosomes

6 Sexual Reproduction (mammal)
Fertilisation is when the two nuclei fuse

7 Sexual Reproduction Note:
Fusion of nuclei forms a zygote containing genetic material from both parents.

8 Sexual Reproduction Notes
Answer Tp ‘Testing Your Knowledge’ in sentences. Collect cut-outs and label the parts draw an ‘X’ where fertilisation occurs Extension work – Success Guide p36-37

9 Sex Cells and Fertilisation

10 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.

11 Genetics The number of chromosomes present in an organisms’ cells depends on its species. e.g Human Male 46 Chromosomes

12 Genetics The thread-like chromosomes are made of a chemical substance called DNA. DNA has two strands which form a twisted structure called a helix. DNA carries coded genetic information. Each piece of information is called a gene.

13 Genetics Notes Copy the definition below:
A gene is a section of a chromosome which contains a separate piece of genetic information.

14 Genetics bases make up a strand of DNA. The order of the bases
A A C T G C C G T A T G Rows of four different bases make up a strand of DNA. The order of the bases makes the DNA code. Adenine (A) Thymine (T) Guanine (G) Cytosine (C)

15 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)

16 Genetics Notes Answer Tp167 Q2 in sentences.
Label the cut-out and stick it in.

17 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.

18 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)

19 Genetics Amino acid Amino acid Amino acid Amino acid Protein molecule
The amino acids are linked together to make a protein. The sequence of amino acids dictates the structure and function of the protein.

20 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.

21 Fertilisation Mini Essay
Describe how and where fertilisation occurs in a flowering plant. For Wednesday 15th December

22 Sex Cells and Fertilisation
Gamete Production

23 Gamete Production Notes
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).

24 Gamete Production Chromatid Centromere Chromatid Chromosome

25 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.

26 Matching chromosomes pair.
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 4 gametes produced.

27 Gamete Production Notes
Answer Tp173 Q2+3 in sentences.

28 Cell ready to divide again
Sperm Mother cell Egg Cell ready to divide again Sperm cell Egg cell MEIOSIS Zygote FERTILISATION

29 Sex Cells and Fertilisation
Sex Determination

30 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.

31 Sex Determination Notes
Complete and stick in the sex chromosomes cut-out.

32 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.

33 Gamete Production Look at Tp175 Q5 (you don’t need to write anything down – just think about the question.)

34 Sex Cells and Fertilisation
Genes and Alleles

35 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.)

36 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.

37 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.

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