C6 (Cell Division) Flashcards
Summary of Organisation of a multicellular organism can be summarised as..
Specialised cells, tissues, organs, organ systems, whole organism
Specialised cells
Cells within multicellular organisms are differentiated/ specialised to carry a very specific function
Erythrocytes
- Red blood cells
- Flattened biconcave shape (increased SA:V ratio)
- Essential to the role of transporting oxygen around body
- No nucleus or other organelles (increase space available for haemoglobin)
- Flexible, can squeeze through narrow capillaries
Neutrophils
- Type of white blood cells, essential role immune system
- Multi-lobed nucleus, easier to squeeze through small gaps to get to site of infection
- Granulas cytoplasm, many lysosomes (contain enzymes to attack pathogens)
Sperm cells
- Male gametes, deliver genetic info to female gamete
- Flagellum, capable of movement, many mitochondria for energy
- Acrosome contains digestive enzymes, digest protective layer around ovum.
Palisade cells
Present in mesophyll, contain chloroplast for photosynthesis
- Rectangular box shape, can be closely packed to form continuous layers
- Thin cell walls, increasing rate of diffusion
- Large vacuole to maintain turgor pressure
- Chloroplasts can move within cytoplasm to absorb move light
Root hair cells
Surfaces of roots near growing tips
Long extensions are called root hairs, increase SA
Maximises uptake of water and minerals from soil
Guard cells
- Surfaces of leaves, from small opening called stomata
- When lose water, become less swollen and close to prevent water loss due to osmotic forces
- Cell wall thicker on one side, does not change symmetrically as vol changes
Tissues
Made up of a collection of differentiated cells . Adapted for particular functions within organisms.
4 main categories of animal tissues:
-Nervous tissue, support transmission of electrical impulses
-Epithelial tissue, covers body surfaces (internal and external)
-Muscle tissue, contracts
-Connective tissue, hold other tissue together or act as transport mediums
Organ systems
- Large multicellular organisms have coordinated organ systems
- Composes of a number of organs working together to carry out major functions
Gaseous exchange system
Extracts oxygen for respiration from air, expels carbon dioxide
Cardiovascular systems
- Moves blood around body
- Effective transport system
Digestive system
Take in food, break down large insoluble molecules into small soluble ones
Absorbs nutrient into blood, retains water, removes undigested material
Squamous Epithelium
- Made up of specialised squamous epithelium cells, known as pavement epithelium due to flat appearance
- Very thin due to squat or flat cells that make it up, one cell thick
- Present when rapid diffusion essential, forms lining of lungs
Ciliated epithelium
- Cilia epithelial cells
- Hair like structure called cilia, move in rythmic manner (lines the trachea)
- Goblet cells, release mucus, trapping unwanted praticles
Cartilage
- Connective tissue found in ear, nose, between bones
- Contains fibres of elastin and collagen
- Firm, flexible connective tissue compound of chondryate cells embedded into extracellular matrix
Muscle
- Contract in order to move body
- Different types of fibres: (skeletal muscles, connect to bones)
- Contain myofibrils which contain contractive proteins
Number of different plant cell tissues
Epidermis tissue (covers plant surfaces)
Vascular tissue (transport water and nutrients)
Epidermis
Single layer closely packed cells covering surface
Usually covered by waxy, waterproof cuticle to reduce water loss
Xylem tissue
Vascular tissue responsible for transport of water and mineral
Composed of vessel elements, elongated dead cells
Walls strengthened with lignin, provides support
Phloem Tissue
Vascular tissue responsible for transport of organic nutrients (particularly sucrose)
Composed of columns of sieve tube cells separated by performed walls called sieve plates
Inside the cell (stages)
Cell, nucleus, chromosomes, DNA, section of DNA is a gene
Diploid mother cell (meaning)
Has a full set of DNA
(In process of cell division the diploid mother cell will replicate the whole set of DNA. One full set in each diploid daughter cell).
What is the function of the spindle fibres
The pull the chromosome to opposite poles
Why must the DNA be replicated in mitosis
Because it’s necessary when all daughter cells have to be identical. This is the case during growth, replacement and repairs of tissues.
Cell cycle
- Gap phase 1 (cell groups and new organelles and proteins are made)
- G1 checkpoint (The cell checks chemicals needed replication present and for any damage to DNA before entering S-phase)
- Synthesis (cell replicates DNA ready to divide by mitosis)
- Gap phase 2 (cell keeps growing and proteins needed for cell division are made)
- G2 Checkpoint (cell checks if all DNA ha s been replicated without damage)
- M Phase (mitosis and cytokinesis)
- Metaphase checkpoint
Cancer
A group of many different diseases caused by uncontrolled division of cells.
Tumours
Types
An abnormal mess of cells
Benign (stops growing and don’t travel to other regions of body)
Malignant (continues to grow unchecked and uncontrolled, the basis of cancer)
What are tumours often a result of?
Damage or spontaneous mutation of the genes that encode the proteins that are involved in regulating the cell cycle, including the checkpoint proteins.
Interphase
Cell carries out normal functions, but also preps to divide.
Cells DNA unravelled and replicated (and its organelles).
ATP content increased
Meiosis ll (second division)
-The 2 daughter cells undergo Prophase ll, Metaphase ll, Anaphase ll, Telophase ll and cytokinesis.
- In anaphase ll the pairs of sister chromatids are separated, each new daughter cell inherits one chromatid from each chromosome
- 4 genetically different haploid cells (gametes)
Prophase
Chromosomes condense (shorter and fatter). Tiny bundles (centrioles) start moving opposite ends, forming network of protein fibres (the spindles). Nucleus envelope breaks down and chromosomes lie free, cytoplasm
Metaphase
The chromosomes (each with 2 chromatids) line up along middle at the spindle equator, become attached to the spindle by their centromere. At metaphase checkpoint (cell checks all chromosomes are attached to spindle fibres before mitosis can continue).
Anaphase
Centromeres divide, separating each pair of sister chromatids
Spindles contract pulling chromatids to opposite ends of the cell, centromere first.
Telophase
Chromatids reach opposite poles on the spindle fibres
Uncoil and become long again (now called chromosomes)
Nuclear envelope forms around each pair of chromosomes (now 2 nuclei)
Cytokinesis
Cytoplasm divides (get two identical daughter cells, genetically identical to original cell and each other) Cytokinesis usually begins at Anaphase, ends Telophase (a separate process to mitosis)