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Starter – Genetic engineering recap. Why are enzymes important in genetic engineering?. Overview. Enzymes are used to cut out the desired gene , cut open the host DNA and join the new gene with the host DNA Thinking Points How does one cell become many to form a human being?
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Starter – Genetic engineering recap Why are enzymes important in genetic engineering?
Overview Enzymes are used to cut out the desired gene, cut open the host DNA and join the new gene with the host DNA Thinking Points • How does one cell become many to form a human being? • How is this linked to reproduction?
Learning Objective and Success Criteria LO: - Explain what are mitosis and meiosis Progress Step 1: Recall the difference between mitosis and Meiosis in terms of cell division Progress Step 2: Correctly use key words such as haploid, diploid, gametes, mitosis and meiosis Progress Step 3: Explain the step by step process of mitosis and meiosis Increasing Difficulty
Chromosomes Long strands of genetic info (DNA) found in nucleus Chromosomes come as identical homologous pairs. (Except sex chromosomes) In cell division chromosomes can be seen to look like a cross 23 pairs in the human body (46 all together) - How many from Mum, how many from Dad?
Making New Cells New cells are needed for an organism of part of an organism. When are new cells needed? They are needed to replace worn out and repair damaged cells. What needs to be achieved from cell division? The new cells must be the same as the originals, so they can do they can do the same job.
Mitosis This is the type of cell division that happens in normal body cells. It results in a cell splitting into two identical cells. (daughter cells) In some parts of a plant or animal it happens rapidly all of the time – skin.
Mitosis The diploid cell has two sets of chromosomes Each chromosome is copied When the cell divides in two each cell gets one copy of each chromosome The nuclei contain two copies of each chromosome. They are diploid cells!
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Chromosomes line up ready for division. Chromosomes in nucleus are copied. Cell division starts and chromosomes start to separate. 2 identical diploid daughter cells produced. Summary...
Learning Checkpoint Using the worksheet describe what Mitosis is. • Chromosomes • Nucleus • Cell division • Diploid • Daughter Cells
Differentiation What does the term mean? • In early development of animal and plant embryos, cells are very unspecialised. • Each type of cell (stem cell) that can turn, differentiate into a type of cell that is needed. • Cells become specialised in early life. By the time a human baby is born, most of the cells are specialised for a particular job, e.g Liver cells. • How will liver cells divide? • What would be produced as a result?
Meiosis is EVERYTHING to do with the production of sex cells! How many chromosomes do you inherit from Mum and how many from Dad?
Meiosis This occurs in the sexual organs to produce gametes. The chromosome number is reduced by half. Each of the 4 gametes produced are slightly different from each other.
Chromosomes are copied by a cell in the reproductive organs. 4 gametes are genetically different. There is variation. The cell divides into two new cells The cells divide to produce 4 haploid daughter cells (gametes)
Meiosis is EVERYTHING to do with the production of sex cells!
Learning Checkpoint Using the worksheet describe what meiosis is. • Sexual reproduction • Gametes • Haploid • Chromosomes
