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Cell Biology - Coggle Diagram
Cell Biology
Microscopy
Light Microscopes
use light and lenses to form an image of a specimen and magnify it
let us see individual cells like nuclei
Electron microscopes
have a much higher magnification than light microscopes and a higher resolution
let us see much smaller things in more detail
magnification= image size/real size
Required Practical - Light Microscope
Add drop of water to clean slide.
Cut up onion and separate layers. Use tweezers to peel off epidermal tissue from bottom of layer.
3.Use tweezers to place epidermal tissue into water on slide.
Add drop of iodine solution (stain) to highlight object in cell.
Place cover slip on top
Use light microscope to view cell.
7.Place slide onto microscope stage
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Eukaryotic Cells
Complex
Animal cells
Cell Membrane
Holds the cell together
Controls what goes in and out
Mitochondira
Where most of the reactions for aerobic respiration take place
respiration transfers energy that the cells need to work
Cytoplasm
gel-like substance where most of the chemical reactions happen
contain enzymes that control the chemical reactions
Nucleus
contains genetic material that controls the activities of the cell
Ribosomes
where proteins are made
Plant cells
Cell wall
made of cellulose
supports the cell and strengthens it
Permanent Vacuole
Contains cell sap
Chloroplasts
where photosynthesis occurs, which makes food for the plant
contain chlorophyll which absorbs the light needed for photosynthesis
Prokaryotic cell
small & simple
Bacterial cell
cell membrane
cytoplasm
cell wall
small rings of DNA called plasmids
no nucleus - single strand of DNA
Specialisation
Examples
Sperm cells
specialised for reproduction
Function= to get the male DNA to the female DNA. Has a long tail and a streamlined head to help it swim to the egg. Lots of mitochondria in the cell to provide energy needed. Carries enzymes in its head to digest through the egg cell membrane.
Nerve cells
specialised for rapid signalling
Function= to carry electrical signals from one part of the body to another. These cells are long to cover more distance and have branched connections at their ends to connect to other nerve cells and form a network throughout the body.
Muscle cells
specialised for contraction
Function= to contract quickly. these cells are long so that they have more space to contract and contain lots of mitochondria to generate the energy needed for contraction.
Root hair cells
specialised for absorbing water and minerals
Cells on the surface of plant roots. Large surface area for absorbing water and mineral ions from the soil.
Phloem & Xylem Cells
specialised for transporting substances
Function= form tubes which transport substances such as food and water around plants. Xylem cells are hollow. Phloem cells have few subcellular structures, so substances can easily flow through.
The Cell Cycle
A series of stages in which cells divide to produce new cells
Stages
Before a cell divides it: Grows in size.
Increases amount of subcellular structures e.g mitochondria & ribosomes.
Duplicates its DNA.
Mitosis = stage when cell divides. 1. One set of chromosomes is pulled to each end of the cell and the nucleus divides.
Cytoplasm and cell membranes divide to form identical cells.
Mitosis allows multicellular organisms to grow or replace cells that have been damaged.