Microscope / Cell structure - function - division Flashcards
the two types of microscope
- light microscope
- electron microscope ( two types )
transmission electron microscope
scanning electron microscope
Using a Microscope
- Place the slide on the stage and secure it with the clips
- Switch on the light
- Use low power
- Focus using the coarse knob
- Focus using fine focus knob
- Repeat using the high power and objective fine focus only
Magnifying Power
High power = Eyepiece * Objective = 10 * 40 = 400
plant cell
middle lamella cell wall cytosplasm ribosome permanent sap vacule cell membrane nucleus mitochondria chloroplast
animal cell
cell membrane nucleus cytoplasm temporary vacuoles mitochondria ribosome
Cell Wall
only in plant cells; made of cellulose this supports cell, gives it shape and prevents it bursting
Cell Membrane
selectively permeable i.e. only allows certain substances through
Mitochondrion
produces energy in the form of ATP using aerobic respiration
chloroplast
only found in plant cells. This is where photosynthesis occurs.
nucleus
control all of the cell’s activities
Nucleolus
makes the components of ribosomes.
Nuclear Pores
allow mRNA to leave the nucleus.
ribosome
make proteins by joining large
numbers of amino acids together
DNA
stores the information needed to make proteins
vacule
A large permanent vacuole only found in plant cells. It stores food, water and waste products
Protoplasm
all of cell, including the cell membrane except the large vacuole in plant cells
cytosol
cytoplasm minus the organelles.
cytoplasm
contains living material outside the nucleous
site of fermentation and glycolysis
Prepare and Examine an Animal Cell (Cheek Cell)
A. prepare a slide rub a wooden spatula inside your cheek transfer it to a slide add a drop of water place cover slip at an angle and lower it onto the slide to prevent air bubbles being trapped add drop of methylene blue stain draw stain using tissue paper stain deepens colour of the structure easier to see
B. examine the slide
place the slide on the stage
switch on the light
examine at low power and focus using the coarse focus knob
Examine at medium and high power but only use the fine focus
Prepare and Examine a Plant Cell (Onion Cell)
A. prepare a slide
- Cut onion in half, remove a layer and peel off thin skin of cells
- Cut a small square of this skin and place on a clean microscope slide using a paintbrush
- Add a drop of water
- Place cover slip at an angle and lower onto slide to prevent air bubbles
- Add a drop of iodine stain at one side of cover slip
- Draw stain through using tissue paper at other side
- Note stain deepens the colour of structures and makes them easier to see
B. examine a slide
- Place the slide on the stage and clip in place
- Switch on the light
- Examine at low power and focus using the coarse focus knob
- Examine at medium and high power but use the fine focus only
Prokaryotic cells
No nuclear membrane
No membrane-bound structures
e.g bacteria
Eukaryotic
Have a nuclear membrane
Have membrane bound organelles
eg. amoeba
Cell
basic unit from which all living things are built and is the smallest entity that has all the
characteristics of life.
Tissue
group of similar cells with a common function
Tissue Culture and its uses
Growth of cells in a sterile nutrient medium outside the organism
uses including
1) Growing skin epidermis for grafting
2) Cancer research
3) Micropropagation of plants
Organ
Group of different tissues working together to carry out a particular function
Organ System
Group of organs working together to carry out a particular function
Cell Continuity
all new cells are made by the division of existing living cells.
Chromosome
thread-like structure made of DNA and protein,
containing genetic information (genes) which passed from one generation to the next
- Diploid
* Diploid number
a cell containing two sets of chromosomes
number of chromosomes in a diploid nucleus
e.g. humans 2n = 46 made up of 23 pairs
haploid
haploid number
a cell containing one set of chromosomes
the number of chromosomes in a haploid nucleus e.g. humans n = 23
Cancer
possible causes
a group of disorders in which body loses control of the normal regulation of mitosis
radiation
carcinogenic chemicals
viruses
mitosis
the division of a nucleus to form two nuclei genetically identical to the original and thus to each other
- Maintains chromosome number
- Two identical daughter cells
Functions of Mitosis
- In Single-celled organisms its function is reproduction.
2. In Multicellular organisms its function is growth and repair
Stages of Mitosis
- I Party Monday And Tuesday
Interphase (not part of mitosis)
cell spends almost all of its time in this stage
1. The chromosomes are spread out and cannot be seen as discrete structures
2. The cell grows and synthesises (makes) proteins
3. Cell organelles, mitochondria, chloroplasts etc. replicate,
and the DNA also replicates
Prophase
- The Chromatin condenses into double stranded chromosomes
- The Nuclear membrane starts to break down
- The Centrioles begin to move to opposite poles and spindle fibres start to form
metaphase
- Chromosome arranged on equatorial plate
- Spindle fibres attached to centromeres
- No nuclear membrane
anaphase
- Spindle fibres contract
- Pull chromosomes (sister chromatids) apart at centromeres
- One copy of each chromosome goes to each pole
telophase
- Two identical groups of chromosomes at either pole of cell
- New nuclear membranes form
- Chromosomes uncoil to chromatin
Cytokinesis (not really part of mitosis)
- In Animal cells the cytoplasm divides between two nuclei (cleavage furrow) and new cell membranes form
- In Plant cells a cell plate forms and this becomes a cell wall between the two nuclei
meiosis
division of a diploid nucleus producing four haploid genetically different nuclei
functions of meiosis
- Gamete Formation: Production of haploid sperm and egg cells in humans
- Pollen Grain Formation: In flowering plants
end results of Mitosis and Meiosis
Mitosis
2 cells
Genetically identical
Same number of chromosomes as parent cell
Meiosis
4 cells
All genetically different
Half the number of chromosomes of the parent cell
