✅3 - Cell Structure Flashcards
Describe the structure of the nucleus:
A nucleolus within a nuclear envelope and surrounded by nucleoplasm
Describe the function of the nucleus:
- contains the genetic material
- controls the cell’s activities
Describe the structure of the mitochondria :
Rod shaped double membrane bound structures with a folded inner membrane and matrix
Describe the function of the mitochondria:
- sites of aerobic respiration
- production of ATP
Describe the structure of the chloroplasts:
A double membrane bound organelle with stacks of thylakoids (grana) all connected by lamellae
Describe the function of the chloroplasts:
-to harvest sunlight for photosynthesis
Describe the structure of the Golgi apparatus + vesicles:
A stack of membranes that make up flattened stacks, or cisternae
Describe the function of the Golgi apparatus + vesicles:
- add carbohydrates to proteins to form glycoprotiens
- transport, modify and store lipids
- produce secretory enzymes
- secrete carbohydrates
- make lysosomes
Describe the structure of the lysosomes:
Golgi vesicles which contain enzymes such as proteases and lipases (lysozymes)
Describe the function of the lysosomes:
- digest worn out organelles (using lysozymes)
- break down cells completely after they’ve died
- hydrolyse material ingested by phagocytic cells
Describe the structure of the ribosomes:
Small cytoplasmic granules, with ribosomal DNA and protein
Describe the function of the ribosomes:
-the site of protein synthesis in the cell
Describe the structure of the RER and SER:
RER: Three dimensional sheet like membranes continuous with the outer nuclear membrane, studded with ribosomes
SER: Three dimensional sheet like membranes continuous with the outer nuclear membrane, no ribosmes
Describe the function of the RER and SER:
RER: -provides large surface area for synthesis of proteins and glycoprotiens
-provides pathway for transport of materials. especially proteins, throughout the cell
Describe the structure of the cell wall:
Microfibrils of cellulose embedded in a matrix
Describe the function of the cell wall:
-provides mechanical strength to prevent the cell bursting when water enters by osmosis
Describe the structure of the vacuole:
A single membrane bound sac filled with cell sap (sugars and salts)
Describe the function of the vacuole:
- temporary food store
- keeps cells turgid
How do prokaryotic cell differ from eukaryotic cells in terms of size?
The are much smaller
How do prokaryotic cell differ from eukaryotic cells in terms of organelles?
The have no membrane bound organelles
How do prokaryotic cell differ from eukaryotic cells in terms of nuclei?
The don’t have a nucleus, instead a singular circular DNA molecule, free in the cytoplasm and not associated with any proteins.
How do prokaryotic cell differ from eukaryotic cells in terms of cell membrane
It contains murein, a glycoprotien (In the cell wall)
What other features may a prokaryotic cell have?
- one or more plasmids
- a capsule surrounding the cell
- one or more flagella
Viruses are…
…acellular and non-living
Describe the structure of a virus:
They include genetic material, capsid and attachment protein
Describe the principles of an optical microscope:
Creates a magnified image of an object specimen with an objective lens and magnifies the image further with an eyepiece.
Light source —-> condenser lens —-> object —-> objective lens —-> intermediate image —-> eyepiece lens—-> eye
Describe the limitations of an optical microscope:
- the resolution is only half the wavelength of visible light
- magnification is relatively low
- the surface view is not always very clear
Describe the principles of an transmission electron microscope:
Electron gun focuses a beam of electrons onto the specimen using a condenser electromagnet. It passes through a thin section of the specimen.
Electron source —-> magnetic condenser —-> object —-> magnetic objective —-> intermediate image —-> magnetic projector —-> fluorescent screen
Describe the principles of an transmission electron microscope:
Electron gun focuses a beam of electrons onto the specimen from below using a condenser electromagnet. It passes through a thin section of the specimen.
Electron source —-> magnetic condenser —-> object —-> magnetic objective —-> intermediate image —-> magnetic projector —-> fluorescent screen
Describe the limitations of a transmission electron microscope:
- The whole system must be in a vacuum so living things can’t be observed
- Complex staining processes are involved, and the image is still in black and white
- Specimen must be thin
- The image may contain artefacts
Describe the principles of a scanning electron microscope:
Directs a bean of electrons on to the surface from above rather then below. Beam passed back and forth in a regular pattern, electrons are then scattered
Describe the limitations of a scanning electron microscope:
- The whole system must be in a vacuum so living things can’t be observed
- Complex staining processes are involved, and the image is still in black and white
- The image may contain artefacts