M2C6 - Cell Division Flashcards
Cell Division
What is mitosis
The process of nuclear division by which two genetically identical daughter nuclei are produced.
What is the role of mitosis
Growth, Repair and Asexual Reproduction
What are the stages of the cell cycle
Interphase
Nuclear Division - Mitosis
Cell division - Cytokinesis
Name the Stages of Mitosis
(Interphase)
Prophase
Metaphase
Anaphase
Telophase
(Cytokinesis)
Prophase
Chromosomes condense and become visible when stained.
Chromatids are joined together at the centromere.
Two centrosomes move towards opposite poles.
Spindle fibres begin to form from the centrosome.
Nuclear envelope begins to break down.
Nucleolus disappears.
Metaphase
Centrosomes reach opposite poles.
Spindle fibres continue to extend from centrosomes.
Chromosomes line up at the equator (metaphase plate) of the spindle.
Spindle fibres (protein microtubules) reach the chromosomes and attach to the centromeres (kinetochores).
Each sister chromatid is attached to a spindle fibre originating from opposite poles.
Anaphase
The sister chromatids separate at the centromere.
Spindle fibres bein to shorten.
Chromatids are pulled to opposite poles by the spindle fibres.
Telophase
Chromosomes arrive at opposite poles and begin to decondense.
Nuclear envelope begins to reform.
Spindle fibres break down.
New nucleoli form within each nucleus.
What is meiosis
Meiosis is a form of nuclear division that produces gametes which are haploid cells from a diploid cell.
What are the stages of meiosis
(Interphase)
Prophase 1
Metaphase 1
Anaphase 1
Telophase 1
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2
(Cytokinesis)
Prophase 1
DNA condenses and becomes visible as chromosomes.
Chromosomes are arranged in homologous pairs (bivalent).
Crossing over occurs (chiasma)
Spindle is formed.
Nuclear envelope breaks down
Metaphase 1
Homologous pairs line up along the equator of the spindle.
Independent assortment occurs.
Anaphase 1
Homologous pairs are separated as microtubules pull the chromosomes to opposite ends.
Telophase 1
Chromosomes arrive at opposite poles.
Spindle fibres break down.
Nuclear envelope forms around two groups of chromosomes and nucleoli reform.
Cytokinesis
The division of the cytoplasm.
Cell surface membrane pinches inwards creating a cleavage furrow in animals.
Vesicles from the Golgi apparatus gather along the equator of the spindle and merge with each other to form the new cell surface membrane in plants.
Prophase 2
Nuclear envelope breaks down and chromosomes condense.
Spindle forms at a right angle to the old one.
Metaphase 2
Chromosomes line up along the equator of the spindle.
Anaphase 2
Centromeres divide and individual chromatids are pulled to opposite poles.
Telophase 2
Nuclear membranes form around each group of chromosomes.
Cytokinesis
Cytoplasm divides as new surface membranes are formed creating 4 haploid cells.
Crossing over
The process by which non-sister chromatids exchange alleles. It increases genetic diversity of gametes during meiosis. It can result in a new combination of alleles on the two chromosomes.
Independent assortment
The production of different combinations of alleles in daughter cells due to the random alignment of homologous pairs along the equator of the spindle during metaphase 1.
Function of an erythrocyte
Transport oxygen around the body and carbon dioxide to the lungs
Adaptations of erythrocytes
Biconcave shape which increases the surface ares over which oxygen can be absorbed.
Cytoplasm contains high levels of haemoglobin which binds to oxygen.
No nucleus.
Elastic membrane for flexibility through narrow capillaries.
Function of neutrophils
destroy pathogens by phagocytosis and the secretion of enzymes
Adaptations of neutrophils
Flexible shape to fit through cell junctions in capillary walls.
Able to engulf microorganisms.
Large number of lysosomes to aid in digesting and destroying invading cells.
Lobed nucleus for flexibility.
Function of sperm cells
Reproduction
Adaptations of sperm cells
Head containing a nucleus with half the normal number of chromosomes.
Acrosome in head contains digestive enzymes to break down outer layer of an egg cell.
Mid-piece packed with mitochondria to release energy for tail movement.
Rotating tail for movement.
Function of root hair cells
Absorption of water and mineral ions from soil
Adaptations of root hair cells
Root hair to increase surface are so the rate of water uptake by osmosis is grater.
Thinner walls to allow water to move easily through due to shorter diffusion distance.
Permanent vacuole containing cell sap which is more concentrated than soil, maintaining the concentration gradient.
Mitochondria for active transport of mineral ions.
Function of ciliated epithelial cells
Moving substances across the surface of a tissue
Adaptations of ciliated epithelial cells
Cilia which waft in a coordinated way to shift material along the surface of the epithelium tissue.
Goblet cells secrete mucus to trap dust, dirt and microorganisms.
Function of squamous epithelium
Provide a surface covering the outer layer.
Adaptations of squamous epithelium
Single layer of flattened cells on a basement membrane.
Thin cross section which shortens diffusion pathway.
Permeable, allowing for easy diffusion of gases.
Function of palisade cells
Carry out photosynthesis
Adaptations of palisade cells
Large number of chloroplasts for light absorption.
Tall and thin shape to allow greater light penetration depth
Function of guard cells
Control the opening of the stomata to regulate water loss.
Adaptions of guard cells
Inner cell walls are thinker and outer cell walls are thinner, to allow the cell to bend when turgid.
High density of chloroplasts and mitochondria.
What is a tissue
Specialised cells of the same type group together.
What are organs
Different tissues working together
Function of xylem vessel cells
Transport tissue for water and dissolved ions
Adaptations of xylem tissue
No top and bottom walls between cells to form continuous hollow tubes for transportation.
Cells are without organelles or cytoplasm to allow free movement of water.
Outer walls are thickened with lignin to support the plant.
Function of phloem vessel cells
Transport of dissolved sugars and amino acids
Adaptions of phloem tissue
Made of living cells which are supported by companion cells.
Joined end to end and contain holes in end cell walls forming tubes.
Few subcellular structures to aid flow of materials.
function of muscle cells
Contraction for movement
What are the three different types of muscle in animals?
Skeletal, Smooth and Cardiac
Adaptations for muscle tissue
Layer of protein filaments causing muscle contraction.
High density of mitochondria to provide sufficient energy.
Skeletal muscle cells fuse together during development to form multinucleated cells that contract in unison
Function of cartilage
Support:
It is strong and flexible tissue found in various places around the body, such as the trachea, where it is used to ensure it stays open while allowing it to move and flex whilst breathing.
What is totipotency
Stem cells that can differentiate into any cell type, including embryonic cells.
What is pluripotency
Stem cells that can differentiate into any cell type except for embryonic cells.
What is multipotency
Stem cells that can differentiate into only a handful of cell types.
What is unipotency
Stem cells that can only differentiate into one type of cell
