cell biology Flashcards
(33 cards)
What is the difference between a prokaryotic and eukaryotic cells?
EUKARYOTIC:
•Genetic material (DNA) is enclosed within a nucleus
•Between 10 and 100 µm
•Have organelles which carry out functions
•Examples include animals, plants, and fungi cells
PROKARYOTIC:
•Genetic material is NOT inclosed in a nucleus but in a single loop of DNA in cytoplasm
•Plasmids are also present
•Cell membranes are surrounded by a cell wall
•~ 1 µm in size
What is cytoplasm?
A jelly-like material which is the site of chemical reactions
What is a nucleus?
Controls DNA and cell activity
What is a cell membrane?
Controls the movement of substances in and out of the cells as it is permeable to certain substances
What is mitochondria?
Where energy is released in respiration
What are ribosomes?
The site of protein synthesis
What are chloroplasts?
They contain chlorophyll to absorb light for photosynthesis
What is the cell wall?
It strengthens plant cells
What is a vacuole?
It is filled with sap to keep plant cells turgid
REQUIRED PRACTICAL: light microscopes
Magnification=image size/real size
unit: µm (micrometees)
Method
1. Put the slide on the microscope stage and select the lowest power objective lens (this is usually ×4
objective lens). The end of the objective lens needs to almost touch the slide.
2. Turn the coarse adjustment knob to move the lens towards the slide. Look from the side (not through
the eyepiece) when you are adjusting the lens.
3. Look through the eyepiece. Slowly turn the coarse adjustment knob in the direction to increase the
distance between the objective lens and the slide. Do this until the cells come into focus.
4. 5. 6. When you have found some cells, switch to a higher power lens (×100 or ×400 magnification).
You will have to use the fine adjustment knob to bring the cells back into focus.
Make a clear, labelled drawing of some of the cells. Make sure that you draw and label any component
parts of the cell. Use a pencil to draw the cells. Write the magnification underneath your drawing
What is a specialised cell?
Cells may be have a specialised structure to carry out a particular function
What is the function of sperm cells?
How are they adapted?
FUNCTION: To get the male DNA to the female DNA.
ADAPTATION: Streamlined head, long tail, lots of mitochondria to provide energy.
What is the function of neurons?
How are they adapted?
FUNCTION: To send electrical impulses around the body
ADAPTATION: Long to cover more distance. Has
branched connections to connect
in a network.
What is the function of muscle cells?
How are they adapted?
FUNCTION: To contract quickly
ADAPTATION: Long and contain lots of mitochondria for energy
What is the function of root hair cells?
How are they adapted?
FUNCTION: To absorb water
from the soil
ADAPTATION: A large surface area to absorb
more water
What is the function of phloem?
How are they adapted?
FUNCTION: Transports substances around the plant
ADAPTATION: Pores to allow cell sap to flow. Cells are long and joined end to end
What is the function of xylem?
How are they adapted?
FUNCTION: Transports water through the plant
ADAPTATION: Hollow in the centre. Tubes are joined end to end
What are the differences between light and electron microscopes?
LIGHT:
•magnification- x1500
•resolution- 200nm
ELECTRON:
•magnification- x1,000,000
•resolution- 1nm
REQUIRED PRACTICAL: culturing microorganisms
Method
1. Make sure your hands and work space are thoroughly clean before and after the experiment.
2. Use a permanent marker to mark the bottom of the nutrient agar plate (not the lid). Make sure that the lid stays in place to avoid
contamination.
3. Divide the plate into three equal sections and number them 1, 2 and 3 around the edge. Add your initials, the date and the name of the bacteria.
4. Put a different antiseptic onto each of three filter paper discs, being careful to shake off excess liquid to avoid splashing.
5. Carefully lift the lid of the agar plate at an angle away from your face. Do not open it fully.
6. Use the forceps to carefully put each disc onto each section. Make a note of which antiseptic is in each section.
7. Secure the lid of the agar plate in place using two small pieces of clear tape. Do not seal the lid all the way around as this creates anaerobic conditions. Anaerobic
conditions will prevent the bacteria from growing and can encourage some other very nasty bacteria to grow.
8. Incubate the plate at 25 °C for 48 hours and store upside down to prevent water condensing on the agar and disturbing the bacteria growth.
9. Measure the diameter of the clear zone around each disc. Measure again at 90° to your first measurement, then calculate the mean diameter
Explain the process of cell division
CELL GROWTH: Before a cell can divide it needs to
grow and increase the number of sub-cellular
structures such as ribosomes and mitochondria.
COPYING OF CHROMOSOMES: The DNA replicates
to form two copies of each chromosome.
MITOSIS: one set of chromosomes is pulled to
each end of the cell and the nucleus divides.
Finally the cytoplasm and cell membranes divide
to form two identical cells
What is a stem cell?
A stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can
arise from differentiation
What is an embryonic stem cell?
A cell taken from an embryo which can differentiate into any kind of cell
What is an adult stem cell?
Cells from the adult body which can only differentiate into certain cells (eg. bone marrow cells can only differentiate into blood cells or immune system cells)
Where does plant cell division occur?
Meristems
