2.1.1. Cell Structure Flashcards
Eukaryotic cells
Have a nucleus (containing chromosomes of DNA and histone proteins) inside a nuclear envelope and other membrane-bound organelles
Typically form tissues in multicellular organisms
What is resolution
The clarity of an image- higher the resolution, clearer the image
Magnification
The number of times larger an image appears compared to actual size
Drawing cells
50% of page 4/5 cells Include wall and membrane and nucleus Joined neatly Label lines with ruler Pencil
Antonie van Leeuwenhoek
Dutch microscopist who discovered bacteria and created his own microscopes
Unicellular organisms
Consist of a single cell in which all characteristic activities take place e.g.- brewers yeast
Multi-cellular organisms
Composed of many cells
Specialised cell formed
From a cell during cell differentiation
Tissue
Collection of cells together with any intercellular secretion produced by them, that’s specialised to form a particular function or task. Cells may be the same type or mixed type
Organ
A group of tissues that carry out one function
Organ system
Groups of organs and tissues carrying out one function
Features of animal cell under light microscope
Nucleus (containing chromatin) Nuclear envelope Cell surface membrane Cytoplasm Glycogen granules
Features of plant cell under light microscope
Nucleus Cell surface membrane Tonoplast membrane Chloroplasts Vacuole (contains cell sap) Starch granules Cytoplasm Cellulose cell wall
Typical plant cell
Mesophyll cell from a leaf
Typical animal cell
Liver cell from mammal
Under light microscope both animal and plant cells contain
Cell surface membrane Cytoplasm Nucleus Nucleolus Mitochondria Endoplasmic reticulum Golgi body
Microscope calibration
Calibrated using eyepiece graticule
Graticule remains constant no matter the magnification
A microscope ruler on special slide (stage micrometer) is placed on microscopes stage
Division of labour
In cells each type of organelle has a specific role which work together, each contributing it’s part to the survival
Cytoskeleton
A network of fibres made of protein that keep the cells shape stable by providing an internal framework
Food energy reserves (pro)
stored in granules and vacuoles
1 micrometer = mm
1/1000 mm
1 nanometer = micrometers
1/1000 micrometers
magnification of scale bar =
length of scale bar / length of s.b. represents
eyepeice graticule
a measuring device placed in the eyepiece to act as a ruler when viewing an object
stage graticule
small scale placed on microscope stage and used to calibrate the value of eyepiece divisions at different magnifications
3 types of fibre in the cytoskeleton
microfilaments, micrtubules, intermediate filaments
roles of the cytoskeleton
structure, transport, cell movement
advantages of staining
highlight a particular organelles, distinguish between different cell types, distinguish different tissue types
stain for cells under a microscope
methylene blue, eosin
