B2 Cells Flashcards
Name 3 components of the plasma membrane
Phospholipids
Proteins
Glycoproteins
Glycolipids
Cholesterol
What organelle contains genetic information?
nucleus
Describe the components of the nucleus
nuclear envelope- double me,brand surrounding nucleus
nuclear pores - gaps in nuclear envelope
nucleoplasm - granular, jelly-like material
chromosomes - make of DNA bound to his tones
nucleolus - inside nucleoplasm
what is the role of the nucleolus
manufactures ribosomal RNA
whats the job of the nuclear pores
allows mRNA to leave nucleus
Whats the approx size of nuclear pores
400 - 100 um
What organelle is found in large number of active cells
mitochondria
What are the cristae made of and what are they for?
Extensions of the inner membrane Enzymes and proteins are attached to it Large surface area for respiration
What is found in the matrix of the mitochondria?
Proteins
Lipids
Ribosomes
DNA
Why do mitochondria have their own ribosomes and DNA?
to make their own proteins
What organelle is found in plant and algae cells but not animal cells?
Cell wall
Cell vacuole Chloroplasts
What are the grana made up of in chloroplasts?
Stacks of thylakoids
What can be found inside thylakoids?
chlorophyll
Explain how chloroplasts are adapted for their function?
Thylakoid membranes provide a large surface area for electron carriers
involved in the first stage of photosynthesis
The stroma contains the enzymes needed for the second stage of photosynthesis
Chloroplasts contain DNA and ribosomes so they can quickly make their own proteins
What does the SER do?
Synthesises lipids
- What does the golgi body do?
Modifies proteins (eg forms glycoproteins)
And forms vesicles to transport modified proteins to cell membrane
- What is the function of a cell wall in plant cells?
Provides mechanical strength and prevents lysis when water enters
- What name do we give to a group of similar types of cells working together?
tissues
- What is an organ?
A group of similar tissue working together to perform a function
- What type of cell are animal and plant cells?
eukaryotic
- What type of organelles do prokaryotic cells not have?
no membrane bound organelles
- Describe the DNA in a prokaryote
Short
Circular not linear
Plasmids
Not associated with histones
No introns
- Name 3 structures that make up a virus
Genetic material
Capsid
Attachment protein
- Contrast the structure of a bacterial cell and the structure of a human cell.
- Bacterial cell is much smaller than a human cell;
- Bacterial cell has a cell wall but human cell does not;
- Bacterial cell lacks a nucleus but human cell has a nucleus;
- Bacterial cell lacks membrane-bound organelles but human cell has membrane-bound organelles;
- Bacterial ribosomes smaller than human ribosomes
- Bacterial DNA is circular but human DNA is linear;
- Bacterial DNA is ‘naked’ whereas human DNA is bound to histones / proteins
- What cannot be seen in an optical microscope but can be seen in an electron microscope?
ribosomes
- What can be observed using an optical microscope that cannot be observed using an electron microscope?
Living specimens
Specimens in colour
- Why does an electron microscope have a better resolution than an optical microscope?
Electrons have a shorter wavelength than light
- Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of their use when studying cells.
- TEM use electrons and optical use light;
- TEM allows a greater resolution;
- So with TEM smaller organelles can be seen and in greater detail
- TEM view only dead specimens and optical can view live specimens;
- TEM does not show colour and optical can;
- TEM requires thinner specimens;
- TEM requires a more complex and time consuming preparation;
- TEM focuses using magnets and optical uses (glass) lenses;
- What laboratory process can be used to separate the organelles?
Cell fractionation (homogenisation and ultracentrifugation)
- Explain two conditions needed for the process above.
Cold – slows/stops enzyme activity to prevent digestion of organells
Isotonic (same water potential) – prevents osmosis so no lysis of organelles
Buffered – maintains pH so that enzymes/ proteins not denatured
- Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells.
- Cell homogenisation to break open cells;
- Filter to remove large debris;
- Use isotonic solution to prevent damage to organelles;
- Keep cold to reduce damage by enzymes /
- Use buffer to prevent protein / enzyme denaturation;
- Centrifuge at lower speed to separate heavy organelles;
- Re-spin supernatant at higher speed to get organelle at bottom.
