Cell Structure Flashcards
Eukaryotic cells
Complex cells e.g. Animal or plant cells.
Cells with a true nucleus
Organelles in an animal cell?
- Plasma membrane
- Rough endoplasmic reticulum (RER)
- Smooth ER
- nuclear envelope
- Nucleus
- Nucleolus
- Lysosome
- Ribosome
- Golgi apparatus
- Cytoplasm
- Mitochondria
Organelles in a plant cell?
- Cell wall with plasmodesmata
- Vacuole
- Plasma membrane
- Chloroplast
- RER
- SER
- Mitochondria
- Golgi
- Cytoplasm
- Nuclear envelope
- Nucleolus
- Nucleus
- Ribosome
What organelles does a plant cell have that an animal cell does not?
- A cell wall with plasmodesmata
- Chloroplasts
- Vacuole
What organelles does an animal cell have that a plant cell doesn’t?
Lysosomes
What is plasmodesmata?
Channels for exchanging substances with adjacent cells
Function of plasma membrane
- Regulates movement of substances in and out of the cell
- Has receptor molecules which allow cell signalling through means of chemicals
Function of cell wall
-Supports plant cells
Function of nucleus
- Controls cell’s activities by controlling transcription of DNA
- Contains DNA needed to make proteins
- The pores allow substances (e.g RNA) to move between the nucleus and the cytoplasm
- The nucleolus makes ribosomes
Function of a lysosome
- Contains digestive enzymes
- Keeps the digestive enzymes separate from the cytoplasm by its surrounding membrane
- Can be used to digest invading cells or break down worn out components
Function of ribosomes
-The site where proteins are made
Function of rough endoplasmic reticulum
-Folds and processes proteins that have been made in the ribosomes
Function of the smooth endoplasmic reticulum
-Synthesises and processes lipids
Function of a vesicle
-Transports substances in and out of the cell (via the plasma membrane) and between organelles
Function of the Golgi apparatus
- Process and package new lipids and proteins
- Makes lysosomes
Function of the mitochondria
-Site of aerobic respiration where ATP is produced
Function of chloroplasts
- The site of photosynthesis
- Some parts of photosynthesis happen in the grana and others in the stroma
Function of the centriole
- Involved with the separation of chromosomes during cell division
- Send out spindle fibres
Function of cilia
-They move substances along the cell surface
Function of the flagellum
- It’s microtubules contract to make flagellum move
- Propel cell forward
Where are mitochondria generally found?
In very active cells that require a lot of energy. They are found in large numbers.
What is the name of the membrane inside the chloroplast called?
Thylakoid membrane
What is grana?
Stacked up thylakoid membranes
What are grana linked together by?
Lamellae
What does the inner membrane of a mitochondrion fold to form?
Cristae
Where are the enzymes for respiration in the mitochondrion?
Matrix
Describe protein production in a cell
- Proteins are made in the ribosomes
- New proteins produced at the RER are folded and processed
- Then transported from the RER to the Golgi apparatus in vesicles
- At the Golgi apparatus the proteins may undergo further processing
- The proteins enter more vesicles to be transported around the cell
The four main functions of the cytoskeleton:
- The microtubules and microfilaments support the cells organelles, keeping them in structure.
- They help strengthen the cell and maintain its structure.
- Responsible for movement of materials within the cell e.g. Movement of chromosomes during cell division
- Proteins of the cytoskeleton can also make the cell move
Features of prokaryotes
- Extremely small-less than 2nanometer diameter
- DNA is circular/loop
- No nucleus, DNA is free in the cytoplasm
- Few organelles but none are membrane bound
- Flagellum (when present) made of the protein flagellin, arranged in a helix
- Small ribosomes
Features of eukaryotes
- Larger cells- about 10-100 nm diameter
- DNA is linear
- Nucleus is present, DNA inside
- Many organelles (membrane bound)
- Flagella (when present) is made of microtubule proteins arranged in a ‘9+2’ formation
- Larger ribosomes
Magnification
The number of times larger an image appears, compared to the size of the object
Resolution
The clarity of an image; the higher the resolution the clearer the image
How well a microscope can distinguish between two points
How to calculate magnification of an image
Image size/object size
Prokaryotic cell
Smaller, simpler cells e.g. Bacteria
Lack membrane bound organelles and an organised nucleus
Name the 3 types of microscopes
- Light microscope
- Laser scanning confocal microscopes
- Electron microscope-(TEM and SEM)
Describe how a light microscope works
By using light to observe an image
How high is the resolution of a light microscope?
0.2 micrometers approx. A lower resolution than electron microscopes so they are usually used to look at whole cells or tissue.
Maximum magnification of a light microscope
x1500
Describe how a Laser scanning confocal microscope works
- Uses laser beams (intense beams of light) to scan a specimen, which is usually tagged with a fluorecent dye.
- The laser causes the dye to fluorece
- This light is then focused through a pinhole onto a detector
- The detector is hooked up to a computer, which creates a 3D image
How is sending the LSCM light through a pinhole useful?
It blocks out all the out of focus light so that these microscopes can get a clearer image than light microscopes.
Descibe how an electron microscope works
Electrons are used to form an image instead of light.
Why are electron microscopes better than light ones?
Because they have a higher resolution and can get a more detailed image.
Describe how a Transmission electron microscope works
- Uses electromagnets to focus a beam of electrons, which is then transmitted through the specimen.
- Denser parts of the specimen absorb more electrons, which makes them look darker
Positives and negatives of TEM’s
- Provide high resolution images, so can be used to look at a wide range of organelles.
- Can only be used to look at thin specimens
Describe how a Scanning electron microscope works
- They scan a beam of electrons across the specimen
- This knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image
Describe the image produced by the SEM
- Shows the surface of the specimen and can be 3D
- Gives a lower resolution than TEM’s
