Biology- cells binary fission yr 9

• mitosis is where the chromosomes are separated into two genetically identical daughter cells
• interphase is when the cell grows, replicates its DNA and prepares for division
• the cell cycle is the process by which a single cell divides to produce two daughter cells
• genetic material is made of DNA
• DNA stands for deoxyribonucleic acid
• Strands of DNA are called chromosomes
• Chromosomes are in pairs
• In a human cell, DNA is in the nucleus
• xy= a son
• xx= a daughter
• chromosomes can only be seen when they have been copied, not before
• gene- a short section of DNA which codes for a particular protein/characteristic
• genes are found on chromosmes
• one chromosome comes from each parent
• we have 2 copies of every gene
• 23 chromosomes have 25,000 genes
• Cells divide for different reasons

  1. Growth
  2. To repair tissues (heal)
  3. Asexual reproduction (not humans)
• For a cell to divide it needs to

  1. Chromosomes/dna must be doubled
  2. Organelles must be copied
  3. cells must grow
• Cells go through a series of events called the cell cycle in order to divide
• Cell growth-

  1. chromosomes are copied
  2. organelles (ribosomes, mitochondria) are copied
  3. cell grows
• Interphase is when the cell grows and prepares for division
• Mitosis- the process

  1. Chromosomes are pulled to the opposite ends of the cell
  2. 2 nuclei form
• The stages

  
• uses of mitosis

  1. Used during growth
  2. We can see it in roots, shoots and tips of plants
  3. Also in an embryo after the first few weeks
• The cells of the offspring produced by asexual reproduction are produced by mitosis from parental cells
• the cells of an offspring produces by asexual reproduction are produced by mitosis from parental cells
• tubers- potatoes, runners and spider plantes

  
• daughter cells have the same alleles as parental cells
• runners in plant are genetical clones the come out of the main trunk and can develop into a new plant
• how to figure out the time in mitosis

  length of cell cycle-% time in interphase % time in mitosis

  % time in mitosis/length of cell cycle=decimal time in mitosis

  decimal time in mitosis*length of cell cycle= time in mitosis
• cell division name - binary fission
• differentiation- process when 1 cell changes from 1 type to the other
• stem cells- undifferentiated cells that can divide to produce more cells of the same or different type
• adult stem cells are found in bone marrow
• adult stem cells are multipotent- produce few types of specialised cell
• Embryonic stem cells are totipotent- can differentiate into all types of specialised cell
• in medicine, stem cells are injected into the damaged area, and can even cure things like paralasis
• stem cells replace damaged tissue
• Therapeutic cloning is the process of creating an embryo that has the same genetic material as the patient
• therapeutic cloning stages

  take egg from donor and nucleus from patient

  trigger them to divide

  culture them

  inject into damaged area