Cell structure Flashcards
How are prokaryotic cells different to a eukaryotic cell?
Prokaryotic cells have no membrane-bound organelles
all reactions occur in the cytoplasm
What is an example of a prokaryotic cell?
Bacterial cell
What extra structures do bacterial cells have?
Cell wall
Capsule
Flagella
Pili, fimbriae
How are eukaryotic cells different to a prokaryotic cell?
Have membrane-bound organelles
reactions are organised into these organelles
What are some examples of eukaryotic cells?
Animal cells
Plant cells
What is the structure of a phospholipid molecule?
Head made up of glycerol, phosphate
Tail made up of two fatty acid chains
How do phospholiids react to water? Why?
Are amphipathic - have both hydrophobic and hydrophilic parts
Hydrophilic head because is negatively charged
Hydrophobic tails because are non-polar
What arrangements do phospholipids take in water and oil?
Form a monolayer with heads pointing towards water, tails pointing towards oil
Form a bilayer with heads pointing towards water, tails pointing to each other
What is the structure of the plasma membrane?
Phospholipid bilayer
proteins embedded in the bilayer
What are the types of arrangements of proteins in the plasma membrane? What do they each mean?
Integral - in contact with the hydrophobic core of the bilayer
Peripheral - attached to inner or outer surface of bilayer
What is the glycocalyx?
The oligosaccharide and polysaccharide chains on outside of plasma membrane
What are the oligosaccharride and polysaccharide chains in the glycoclayx attached to? What does this form?
Attached to lipid
forms glycolipid
Attached to protein
forms glycoprotein
What are the functions of the plasma membrane?
Selective permeability
Exocytosis, endocytosis
Signal transduction
What is selective permeability?
Lets some molecules through it
but not others
What does the fluid mosaic model of the plasma membrane mean?
Fluid refers to the phospholipid bilayer being flexible
Mosaic refers to the proteins embedded in the phospholipid bilayer
What is the shape of rough endoplasmic reticulum?
Flat cisternae
What is attached to rough endoplasmic reticulum?
Ribosomes
What is the shape of smooth endoplasmic reticulum?
Tubular shape
Are ribosomes attached to smooth endoplasmic reticulum?
No
What are the functions of smooth endoplasmic reticulum?
Lipid synthesis
Steroid synthesis
Where is smooth endoplasmic reticulum abundant in cells?
Liver
Adrenal glands
Ovaries, testes
What is the function of ribosomes?
Protein synthesis
Where are ribosomes located in the cell? Where do the proteins they produce go?
Cytoplasm, proteins remain there
Attached to rough endoplasmic reticulum, proteins pushed into rough endoplasmic reticulum
What are the two faces of the Golgi apparatus?
Cis face
Trans face
What does the cis face of the Golgi apparatus do?
Recieves transport vesicles from ER
fuses with them
What does the trans face of the Golgi apparatus do?
Secretory vesicles bud off the trans face
move towards plasma membrane
What is the function of the Golgi apparatus?
Modify
sort
concentrate
package proteins synthesised on the rough endoplasmic reticulum
How do primary and secondary lysosomes look different under a microscope?
Primary appears black
Secondary appears grey
Where do lysosomes come from?
The Golgi apparatus trans face
What do lysosomes contain? Give some examples
Hydrolytic enzymes
- proteases
- lipases
- glycosidases
What is the pH inside a lysosome? How is this brought about?
pH = 5
hydrogen ion pump on membrane of lysosome
moves hydrogen ions into the lysosome using energy from ATP —–> ADP + Pi
What is the function of lysosomes?
Fuse with material needing to be digested
break it down
What sort of materials do lysosomes digest? In what processes?
Digest bacteria
in phagocytosis
Digest cell’s own organelles
in autophagy
What types of cells are rich in peroxisomes?
Liver cells
Kidney cells
What is the function of peroxisomes in liver and kidney cells?
Detoxify molecules
e.g. alcohol
How do peroxisomes detoxify molecules such as alcohol?
Oxidise them to form hydrogen peroxide
react them with hydrogen peroxide to form water
What is the structure of a mitochondrion?
Double membrane - inner and outer
intermembrane space between the two
Inner membrane is folded into cristae
Matrix fills the space inside the inner membrane
What does the matrix contain?
Enzymes
Mitochondrial DNA
What does the inner membrane contain? Give an example
Enzymes for electron transport chain, oxidative phosphorylation
e.g. ATP synthase
What is the function of mitochondria?
Release energy by oxidative phosphorylation
What are some examples of cells rich in mitochondria? Why?
Cardiac muscle cells
Sperm cells
because they require lots of energy
Where are mitochondria located in sperm cells?
Wrapped around the tail
What can mitochondria do because they contain their own DNA?
Can divide independently
What is the endosymbiotic theory?
Aerobic bacteria taken up into anaerobic cell
aerobic bacteria developed into mitochondria
What supports the endosymbiotic theory?
DNA and division of mitochondria is similar to bacteria
How are mitochondria inherited?
From mother to offspring
How are actin filaments distributed in the cell?
Cortical distribution - meaning edges
What type of cell are intermediate filaments common in?
Epithelial cells
What is the function if intermediate filaments?
Form a supporting meshwork
Where are intermediate filaments located in the cell?
Cytoplasm
Beneath inner nuclear membrane
Intermediate filaments beneath the inner nuclear membrane is called what?
The nuclear lamina
What is the structure of microtubules?
Hollow cylinders
made up of protein tubulin
Where are microtubules located in the cell?
In movable structures
e.g. cilia, flagella
mitotic spindle
Where do microtubules arise from in ciliated cells?
Basal bodies
Where do microtubules arise from in dividing cells?
Centrosome
How are microtubules arranged in cilia or flagella?
9+2 arrangement
9 fused pairs of microtubules around the egde
2 unfused microtubules in the centre
Arrange the following filaments in order from thickest to thinnest:
- intermediate filaments
- microtubules
- actin filaments
Actin filaments
Intermediate filaments
Microtubules
Where are mitochondria located in cardiac muscle cells?
Between myofibrils
