Cell Division Flashcards
How are Erythrocytes specialised
Flattened biconcave shape to increase SA:V ratio for oxygen transportation
No nuclei, so more room for haemoglobin
Flexible to squeeze through narrow capillaries
How are Neutrophils specialised
A characteristic multi-lobed nucleus to squeeze through small gaps to get to infections
Granular cytoplasm containing many lysosomes containing enzymes to attack pathogens
How are Sperm Cells specialised
A tail/flagellum for movement
Many mitochondria for energy to swim
Acrosome containing digestive enzymes to penetrate egg for fertilisation
How are Palisade Cells specialised
Many chloroplasts for photosynthesis
Cells rectangular so can pack tightly forming a continuous layer
Thin cell walls increasing rate of diffusion of CO2
Large Vacuole to maintain turgor pressure
Chloroplasts can move within cytoplasm to absorb more light
How are Root Hair Cells specialised
Have long extensions (root hairs) increasing SA- maximising uptake of water and minerals from soil
How are Guard Cells specialised
They form stomata to allow CO2 for photosynthesis
Change shape and stoma close to prevent further water loss
Cell wall of guard cell is thicker on one side so cell does not change shape symmetrically as its volume changes
How are Squamous Epithelial Cells specialised
Very flat and thin as one cell thick
Present when rapid diffusion across a surface is essential- forms lining of the lungs and allows rapid diffusion of O2 into blood
Ciliates epithelial cell’s
Mucus swept away by hair like structures from lungs
Mucus traps unwanted particles from reaching alveoli
What does mitosis do
Diploid Identical cells Only chromosomes separate 1 division 2 diploid daughter cells No crossing over No variation
What does meiosis do
Haploid Produces non identical cells Pairs of chromosomes separate 2 divisions 4 haploid daughter cells Crossing over Variation
What are stem cells
Undifferentiated cell’s with the potential to differentiate
Totipotent
Any type of cell
Early embryo
Pluripotent
Most cells
Blastocyst
Multipotent
Many cells
Bone marrow
Sources of stem cells
Umbilical cord
Meristematic tissue
Bone marrow
Embryo
Stages of mitosis
Prophase Metaphase Anaphase Telophase Cytokinesis
What happens in prophase
Chromosomes condense and shorten
Centromeres attach to spindle fibres
Centrioles at opposite ends
What happens in metaphase
Nuclear envelope breaks down
Chromosomes on metaphase plate
What happens in anaphase
Chromosomes become chromatids
What happens in telophase
Nuclear envelope reforms
Chromosomes uncoil
Centromeres and centrioles disassemble
What happens in cytokinesis
Chromosomes coil
Cell membrane and cytoplasm split
Homologous chromosomes
Matching set of chromosomes
Bivalents
Homologous chromosomes pair up
Chiasmata
Chromosomes break and rejoin
