Chapter 3: Cell division Flashcards
Phases of the cell cycle?
Interphase which includes G1, S, G2, phases
What happens in G1 phase?
Cell increases in size, organelles like mitochondria and cytoplasm replicate
What happens in the S phase?
Synthesis phase, the DNA is replicated in the nucleus
What happens in the G2 phase?
Cell continues to grow in size, checks chromosomes for DNA replication errors, repairs them
Why do cells go to the G0 phase?
They’ve been differentiated and can no longer divide, damaged DNA or there are too many cells in the body
What does the G1 and G2 checkpoint do?
Checks if cell is big enough and has been replicated correctly without any errors
Explain the spindle-assembly checkpoint?
Also known as metaphase. Chromosomes are attached to spindles and get aligned along the equator of the cell. Necessary to pass or mitosis can’t happen
Order of mitosis stages?
Prophase, Metaphase, Anaphase and Telophase
Prophase in mitosis?
Chromosomes condense and thicken, this makes them visible. Nuclear envelope starts to break down. Spindle fibres start to form
Metaphase in mitosis?
Spindle fibres move chromosomes into the centre of the cell called the metaphase plate
Anaphase in mitosis?
Centromeres holding the chromatids together separate to either poles by the spindle fibres
Telophase in mitosis?
Chromatids now called chromosomes and assemble at poles. Nuclear envelope starts to form around them. then its cytokinesis.
Where does chiasmata take place and what is it?
Anaphase 1, it is the break and rejoining of chromatids due to them crossing over, cause DNA change and genetic variation
What is crossing over?
Takes place in Prophase 1 and it is the chromatids entangling because they were brought to close together
Where does independent assortment take place and what is it?
Metaphase 1, its chromosomes facing different directions and different poles, cause genetic variation
What happens in Telophase 2?
The chromosomes uncoil and form chromatids again
what is the level of organisation?
Specialised cells, tissue, organs, organ systems, organisms
How are erythrocytes specialised?
Red blood cells, flattened biconcave shape which increases SA:V. No nuclei which means more space for haemoglobin to carry oxygen. Flexible to fit through capillaries
How are neutrophils specialised?
White blood cells essential role in immune system. Multi-lobed nucleus easier to fit through small gaps to reach infections. Granular cytoplasm contains a lot of lysosomes to attack and break down pathogens
How are sperm cells specialised?
Deliver genetic information to female gamete. Have a flagellum = capable of movement. Lots of mitochondria = energy needed to swim. Head of sperm (acrosome) contains digestive enzymes to digest protective layers of the ovum so sperm can penetrate and fertilise egg
How are palisade cells specialised?
Contain A LOT of chloroplasts = absorbs more light via photosynthesis. Closely packed to form continuous layer. Thin cell walls = increases rate of diffusion. Large vacuole to maintain turgor pressure
Root hair cells, how are they specialised?
Present at surfaces of roots near growing tips. Have long extensions (root hairs) which increase SA:V ratio. This maximises the uptake of water and minerals from the soil
How are guard cells specialised?
On the surface of leaves. Form small openings called stomata which allow CO2 to enter plant for photosynthesis. When guard cells loose water = less swollen and change shape to prevent more water loss.
What is cartilage?
Connective tissue. Found at ends and between bones. Flexible and prevents bones from rubbing together and damaging themselves
Name the 4 types tissue in mammals?
Nervous tissue, Epithelial tissue, Muscle tissue and Connective tissue
How is xylem tissue specialised?
Responsible for transport of water and minerals throughout plants. Composed of elongated dead cells. Walls strengthened with lignin. Has rings for structural support too.
3 types of muscle tissue?
Smooth, skeletal and cardiac
2 different types of epithelium
Ciliated and Squamous
How is ciliated epithelium adapted for its function?
Has cilia (hair-like projections) on surface to sweep mucus away from lungs. Goblet cells present to trap unwanted particles
How is squamous epithelium adapted for its function?
Very thin which allows it to have rapid diffusion across surfaces.
How is the phloem specialised?
Transports nutrients around plants. Has sieve tubes within it and companion cells for energy to diffuse in
The name for undifferentiated cells?
Stem cells
How many times can stem cells divide?
As much as they want. Once specialised they loose ability to divide
What does potency mean?
A stem cells ability to differentiate into different cell types. Greater the number the more potent it is
Explain totipotent?
Stem cells that can differentiate into any cell type
Explain pluripotent?
Stem cells that can form all tissue types but not whole organisms. Present in early embryos
Explain multipotent?
Stem cells that can only form a range of cells within a certain type of tissue
What phase does a cell spend most of the time in?
Interphase
Which stage of mitosis is the longest?
Metaphase
Causes for genetic variation?
Mutation, Independent assortment, chiasmata, changes combination of alleles
Cytokinesis?
Cytoplasm dividing
What is the cytoplasm made of?
Cytosol
How many cell divisions for mitosis and meiosis?
Mitosis = 1 cell division and Meiosis = 2 cell divisions
What type of reproduction for both divisions?
Mitosis is asexual and meiosis is sexual
How is the upper epidermis specialised?
Transparent to allow light through onto palisade layer, covered by a waxy cuticle to be waterproof and reduce water loss
Diploid meaning?
Cells with two complete sets of chromosomes
Haploid meaning?
Cells with only one complete set of chromosomes
