2.6 Cell Division and Organisation Flashcards
Homologous pair
- Pair of chromosomes containing a maternal and paternal chromatid joined to together at the centromere
Centromere
- The point on a chromosome attached to a spindle fibre during cell division
Cell cycle stages
- G1 (Gap 1) Growth phase
- Synthesis phase
- G2 (Gap 2) phase
- Mitosis phase
M phase
- involves mitosis and cytokinesis
G1 phase
- Cell grows
- New organelles and proteins are made
G2 phase
- Cell keeps growing
- Proteins needed for cell division are made
Interphase - G1, S, G2
- takes up most of cell division
Interphase - G1, S, G2
- takes up most of cell division
- process of cell growth and DNA replication ready for cell division (m phase)
Mitosis phases
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase
- Chromosomes condense
-
Prophase (Mitosis)
(starting to condense)
- Chromosomes condense
- Centrioles move and spindles form
Metaphase (Mitosis)
(line in centre)
- Nuclear envelope disappears
- Centrioles reach two poles and spindles are complete
- Fully condensed chromosomes
- Centromeres moved to equator
Anaphase
(pulled apart)
- Centromeres split
- Chromatids pulled apart
- Pulled to opposite poles
Telophase
(all at either side)
- Chromatids called chromosomes
- Chromosomes reach poles
- Nuclear envelope forms
- Chromosomes decondense
Cytokinesis
(new cytoplasm formed)
Cytoplasm divides
Mitosis features
- Produces 2 cells
- Genetically identical
- Diploid
Meiosis features
- Produces 4 cells
- Genetically non-identical
- Haploid
Diploid cell
- 46 chromosomes
-
Diploid cell
46 chromosomes
Haploid cells
23 chromosomes
Budding
(How yeast reproduces)
- Bud forms at surface of cell
- Cell undergoes interphase
- DNA and organelles are replicated for the cell to divide - Cell undergoes Mitosis
- Nuclear division is complete
- the budding cell contains a nucleus that has an identical copy of the parent cell’s DNA and a copy of the organelles - The bud separates from the parent cell
producing a new identical yeast cell
Stem cells
- Unspecialised
- Embryonic- totipotent
- Differentiate
- Bone marrow- blood cells
- Cambium- Xylem and Phloem
Totipotent
- Capable of becoming any type of cell in the organism
differentiation
- changes occurring in cells of a multicellular organism
- each different type of cell becomes specialised
- perform a specific function
Ways in which cells can be differentiated
- Number of organelles
- Shape of the cell
- Contents of the cell
Parts of Sperm cell
- acrosome
- Head
- Nucleus
- Mitochondria
- Protein filaments
- tail (undulipodium)
acrosome
- filled with hydrolytic enzymes which can break through the egg
- contains digestive enzymes to enable sperm to penetrate the surface of the egg
Mitochondria
- to provide energy to swim
tail
- swim to female sex cell
Erythrocytes (Red blood cell)
- Bioconcave
- Large surface area for gas exchange
- No nucleus- more room for haemoglobin
- More oxygen can be carried by haemoglobin
Neutrophils (White blood cells)
- defend body against disease
- Flexible shape
- Allows them to engulf foreign pathogens
- Many lysosomes in cytoplasm
- Contain digestive enzymes to break down engulfed particles
Epithelial cells
- Joined by interlinking membranes
- Cilated epithelia in airways have cilia that beat to move particles away
- Squamous epithelia in lungs are very thin to allow efficient diffusion of gases
Root hair cells
- absorb water and mineral ions from soil
- large surface area for absorption
- thin permeable cell wall for entry of water and ions
-Cytoplasm contains extra mitochondria to provide energy needed for activ etransport
tissue
a collection of similar cells working together to carry out a specific function
organ
a collection of similar tissues working together to carry out a specific function
organ system
a collection of similar organs working together to carry out a specific function
Leaves
- Contain palisade tissue for photosynthesis
- conatin epidermal tissue and xylem and phloem in veind
epidermal tissue
prevents water loss from leaf
Palisade cells
- photosynthesis
- contain many chloroplasts absorb sunlight
- Thin walls, CO2 easily diffuse into cell
Guard cells
- pairs with gap between called stoma
- in light, guard cells take up water and become turgid
- thin outer walls and thickened inner walls bend them outwards, opening stomata
stoma
- one of tiny pores in surface of leaf used for gas exchange
Squamous epithelium
- Single layer of flat cells lining a surface
- found in alveoli in lungs
Ciliated epithelium
- layer of cells covered in cilia
- found on surfaces where things need to be moved (trachea)
Muscle tissue
- made up of muscle fibres
- Smooth muscle tissue
- Cardiac muscle tissue
- Skeletal muscle tissue
Smooth muscle tissue
found lining the stomach wall
Cardiac muscle tissue
found in the heart
Skeletal muscle tissue
Use to move
Cartilage
- type of connective tissue found in joints
- Shapes and supports ears, nose and windpipe
- Formed when chondroblasts secrete extracellular matrix which they become trapped inside
Matrix
jelly-like substance containing protein fibres
Xylem tissue
- transports water around plants
- supports plant
- contains hollow xylem vessel cells (dead) and living parenchyma cells
Phloem tissue
- Transports sugars around plant
- arranged in tubes
- made up of sieve cells, companion cells and some ordinary plant cells
