Flashcards in SB2: Cells And Control Deck (65)
Name the two stages of the cell cycle
Interphase and mitosis
List the five stages of mitosis in order
Describe what happens during interphase
The stage when the cell prepares itself for the process of cell division, and DNA replication takes place. The cell also makes more of its sub-cellular structures, and increases in size
Describe what happens during each stage of mitosis
Prophase: the nucleus starts to break down and spindle fibres appear
Metaphase: the chromosomes line up across the middle of the cell
Anaphase: the separated chromosomes move away from each other
Telophase: the chromosomes arrive at opposite ends of the cell and the nucleus membrane reforms
Cytokinesis: the cytoplasm of the cell is separated as the cell membrane is pinched to divide the cell into two daughter cells
Why is mitosis important for an organism?
It is a process of producing genetically identical, diploid cells, needed for growth
What do we call cells that have one copy of each chromosome?
Name three examples of a cell with only one copy of each chromosome
Gametes: egg, sperm, pollen
What do we call cells that have two copies of each chromosome?
Name an example of a cell with two copies of each chromosome
Any body cell (eg. Muscle, epithelial, nerve etc.)
Fruit flys have four types of chromosomes. How many chromosomes are in a diploid fruit fly cell?
Explain why the number of mitochondria in a cell doubles during interphase
So each daughter cell has enough mitochondria/ same number of mitochondria as parent cell
What do we call the offspring from asexual reproduction?
What are spindle fibres and what is their function?
Filaments formed in a cell during mitosis, which help to separate chromosomes
Give a benefit of asexual reproduction
- produces clones
- doesn’t need two parents
- fast method of producing offspring
Give a disadvantage of asexual reproduction
- does not provide variation, so a whole population could get killed by one disease
Describe how mitosis produces genetically identical, diploid cells
The cell copies each chromosome to produce two sets. Each set of chromosomes move to opposite sides of the cell. The cell then splits into two cells, each with a full set of identical chromosomes
Why is each plantlet that grows along a strawberry runner a clone?
Because they are genetically identical to the parent plant/ have the same chromosomes (/DNA/genes) as the parent plant
How can cancers grow?
The cell cycle goes out of control
Describe what a ‘crown gall tumour‘ on a rose plant will look like?
A lump (often brown) on the stem
Explain how crown gall tumours develop
There is a change to the cells that causes rapid and uncontrollable cell division
What is the definition of growth?
An increase in size due to an increase in the number or size of cells
What are percentile curves used for?
The graph shows the expected rate of growth of babies of different birth weights and is used to check that a child‘s growth is normal
What are the three zones of growth in plants?
- zone of cell division (meristem)
- zone of elongation
- zone of differentiation
Name the two types of stem cells in animals
Embryonic stem cells and adult stem cells
Describe the differences between the two types of animal stem cells
Embryonic stem cells can produce any type of specialised cell whilst adult stem cells can only produce the type of specialised cell that is in the tissue around them
Give three advantages of using stem cells to treat people
(1) no need to take anti-rejection drugs because cells are genetically identical
(2) no need to find a donor
(3) no need for tissue typing
Give some disadvantages of using stem cells to treat people
(1) the stem cells may cause cancer if they continue to divide inside the body after they have replaced the damaged cells
(2) cultured stem cells could be contaminated with viruses which would be transferred to a patient
(3) no guarantees that the therapy will be successful
(4) lack of stem cell donors
(5) hard to obtain and store a person‘s embryonic stem cells - need to be collected near the start of the pregnancy
What are the ethical problems of using stem cells to treat people or during research?
- one source of embryonic stem cells is unused embryos produced by ‘in vitro fertilisation‘ (IVF)
- is it right to create embryos for therapy, and destroy them in the process?
- embryos could come to be viewed as a commodity (item), and not as an embryo that could develop into a person
- when should an embryo be regarded as, and treated as, a person?
What are plant stem cells called?