cell structure 2 because i suck Flashcards
In relation to cm give mm, um and nm. [3]
10mm, 10000um, 10000000nm
equation for calculating actual size
a=i/m
Define magnification
The number of times an image is larger than the original
Define resolution
The smallest distance between two points where the two points can still be distinguished
What are the two types of microscope? [2]
Scanning and Transmission
Describe the structure of the nucleus [4]
- Surrounded by nuclear envelope
- Nuclear pores allow more molecules movement
- genetic material is found within, usually as chromatin
- the nucleolus is a region within that synthethises ribosomes
What are the roles of the nucleus? [3]
- To store the genetic material (DNA) of the cell
- To synthesise ribosomes
- Regulate the production of messenger RNA for protein synthesis
What are the functions of the cell surface membrane? [3]
- Encloses the cell to form the boundary between the cytoplasm and the outside environment.
- The control the movement of substances in and out of the cell, as it’s secretively permeable.
- Contains proteins and important molecules for cell signalling and recognition.
How does the structure of the RER relate to it’s function? [2]
- Contains ribosomes on it’s surface for synthesis of proteins
- The RER membranes spread extensively throughout the cell for the transport of proteins
How is the structure of the RER different to the SER?
The smooth endoplasmic reticulum does not have ribosomes on it’s surface.
What is the function of the smooth endoplasmic reticulum?
Synthesises and transports lipids
Describe the structure of mitochondria [4]
- Oval shaped
- Double membrane bound, inner membrane folded into cristae
- contain jelly like fluid called the matrix
- contain circular DNA and 70s ribosomes
What important process occurs at the mitochondria?
Aerobic respiration, which produces ATP. This is used for energy requiring processes
State the function of the golgi body [2]
- Modification and packaging of proteins and lipids for exocytosis or distribution within the cell
- Produces lysosomes
What are lysosomes?
Vesicles from the golgi body that contain digestive enzymes (protease, lipase etc)
List the functions of lysosomes [3]
- Hydrolyse ingested pathogens in phagocytes
- They digest old, worn out organelles in the cells
- Break down cells after cell death
What are the two types ribosome [2]
70s and 80s ribosomes
Where are the two types of ribosomes found? [4]
- 80s ribosomes are found in Eukaryotic cells - in the cytoplasm and on the RER
- 70s ribosomes are found in prokaryotic cells - chloroplasts and mitochondria
Describe the structure of ribosomes [2]
- Contain two subunits
- Each is made up of a ribosomal RNA molecule and a protein
What is the functions of ribosomes?
Protein synthesis
State the function of centrioles [3]
- formation of the spindle during nuclear division
- replicate during cell division
- organise microtubules during mitosis
State the functions of microtubules [2]
- Make up the cytoskeleton
- to give structure and allow transport with the cell
What are microvilli?
Small protrusions of the cell membrane
How do microvilli aid exchange of substances in cells?
They increase the surface area of a cell to increase the efficiency of exchange
Describe the structure of chloroplasts [5]
- Have a double membrane
- Contain a fluid called stroma
- inside, thylakoids are arranged into interconnected stacks of grana
- Contain 70s ribosomes
- Circular DNA
Name the photosynthetic pigment in chloroplasts
Chlorophyll
What is the function of chloroplasts?
Photosynthesis, producing glucose, oxygen and some ATP
Which eukaryotic cells contain a cell wall? [3]
- Plant cells
- algae cells
- fungal cells
What are plant cell walls made up of?
Cellulose
Identify the functions of the plant cell wall [3]
- Provides mechanical strength to the plant
- protects from osmotic lysis
- regulate movement of water
In which type of cell are plasmodesmata found? [2]
- Plant
- Algae
What are the functions of plasmodesmata? [2]
- To allow undisrupted flow of materials via symplastic route
- Efficient exchange fo substances between cells without having to cross the cell wall and membrane
What is the tonoplast
membrane surrounding the large permanent vacuole
What are the functions of the large permanent vacuole [3]
- Stores cell sap
- Maintains turgor pressure
- temporary food storage
Which organelles/cell structures are found in plant cells but not animal [5]
- A cell wall
- Chloroplasts
- Large permanent vacuole
- Tonoplast
- plasmodesmata
What kind of cell are bacterial cells?
Prokaryotic cells
Compare size of Eukaryotic and Prokaryotic cells
P is 1-5um while E is up to 40um
Describe the genetic material of Eukaryotic and Prokaryotic cells
P has circular DNA (plasmid rings) while E has Linear chromosomes associated with histones
Compare the walls of Eukaryotic and Prokaryotic cells
P has peptidoglycan cell walls while E has one made of cellulose
Which cell type has a endoplasmic reticulum?
Eukaryotic
Key features of viruses [4]
- Acellular structures
- Contain nucleic acids surrounded by a capsid
- No organelles or ribosomes (rely on host cell)
- some may have a phospholipid envelope surrounding the capsid
