2.6 Cell cycle Flashcards
What does pluripotent mean?
The cell can differentiate into many types of cells but not all eg. Bone marrow.
What does totipotent mean?
The cell can differentiate into any type of cell eg. embryonic or meristem
Specialised cells: Neutrophils.
Type of leucocyte.
Defend the body against disease.
Flexible shape allows them to engulf foreign particles or pathogens.
Many lysosomes in their cytoplasm which contain digestive enzymes to break down engulfed particles.
Specialised cells: Erythrocytes.
Carry oxygen.
Biconcave disc shape provides a large surface area for gas exchange.
No nucleus so there is more room for haemoglobin
Specialised cells: Epithelial
Cover the surface of organs.
Ciliated epithelial cells have cilia that beat to move particles away.
Squamous epithelial cells are very thin to allow efficient gas exchange.
Specialised cells: Spermatozoons
Have a flagellum so they can swim to the egg.
Lots of mitochondria to provide the energy to swim.
Acrosome contains digestive enzymes to enable the sperm to penetrate the surface of the egg.
Specialised cells: Palisade
Contain many chloroplasts so they can absorb a lot of sunlight.
Walls are thin so that carbon dioxide can easily diffuse into the cell.
Specialised cells: Root hair
Absorb water and mineral ions from the soil.
Large surface area for absorption.
Think, permeable cell wall for entry of water and ions.
Cytoplasm contains extra mitochondria to provide the energy needed for active transport.
Specialised cells: Guard
Found in pairs, with a gap between to form a stoma.
In the light, they take up water and become turgid; their thin outer walls and thickened inner walls force them to bend outwards, opening the stoma.
Tissues: Squamous epithelium
A single layer of flat cells lining a surface.
Tissues: Ciliated epithelium
Layer of cells covered in cilia
Tissues: Muscle
Made up of bundles of elongated muscle fibres.
Contain actin and myosin which form structures called myofibrils.
Either smooth, cardiac, or skeletal.
Tissues: Cartilage
Type of connective tissue found in joints.
Formed when chondroblasts secrete an extracellular matrix.
Tissues: Xylem
Transports water around the plant and gives support.
Tissues: Phloem
Transports assimilates around the plant.
Arranged in tubes and are made up of sieve and companion cells.
Interphase: G1
Growth/gap 1.
Proteins to make organelles are synthesised.
Interphase: S
Synthesis.
Replication of DNA.
Interphase: G2
Growth/gap 2.
Organelles are made and energy stores are increased.
DNA is checked for errors.
It is a checkpoint.
Interphase: G0
When the cell leaves the cell cycle. ‘Waiting area’ for the cell when it doesn’t need to undergo the cycle of replication.
Differentiation; becomes highly specialised and performs this function immediately (stays in G0)
Damaged DNA; G0 stops further replication.
Apoptosis; cellular suicide and will happen in G0.
Mitosis: Prophase
Meiosis: Prophase II
The nuclear envelope breaks down so the chromosomes are free (to an extent) in the cytoplasm.
They condense and become visible.
Centrioles migrate to the poles of the cell to make spindle fibres.
Mitosis: Metaphase
Meiosis: Metaphase II
Chromosomes line up along the equator (metaphase plate) of the cell.
The centriole’s spindle fibres attach to the centromeres of the chromosomes.
Mitosis: Anaphase
Meiosis: Anaphase II
Motor proteins pull and the centromere is split.
One half of the chromosome goes to each side of the cell.
Mitosis: Telophase
Meiosis: Telophase II
A nuclear envelope reforms around the chromosomes so they are no longer visible.
Mitosis: Cytokinesis
Meiosis: Cytokinesis II
Cytoplasm divides into the two identical daughter cells in mitosis or four haploid daughter cells in meiosis
