Cell Ultrastructure Flashcards
Nucleus
Largest membrane bound organelle
Storage and transmission of genetic information
Information within the DNA synthesises the protein for structures and functions of the cell
Double membrane= nuclear envelope which has nuclear pores
RNA moves through nuclear pores
DNA + Proteins = chromatin
What is chromatin
Dense mass of genetic material
What happens to chromatin at cell division
It becomes chromosomes through condensing
Where is the site of oxidative phosphorylation
Mitochondria
What is the structure of mitochondria and what is each of its functions
Outer membrane = lipid synthesis + fatty acid metabolism
Inner membrane = respiratory chain for electron transport
Matrix = kerbs
Intramembranous space = nucleotide synthesis ADP to ATP
Describe the structure of the Golgi apparatus and where is it located
Parallel stacks of membrane
It is located close to the nucleus but usually cannot be seen only seen in plasma cells
What is the function of the Golgi apparatus
Processes and modifies macromolecules synthesised in the endoplasmic reticulum
What are the 3 parts that make up the Golgi apparatus and what are there individual functions
Cis-golgi = nuclear facing, protein phosphorylation, receives from the rough endoplasmic reticulum
Medial = forms complex oligosaccharides by adding sugars to lipids and peptides
Trans-golgi = proteolysis of peptides into active forms and store molecules in the Golgi vesicles which bud from the surface
Describe the structure of the rough endoplasmic reticulum
Highly folded membrane
Rough surface due to ribosomes attached to the surface
What is the function of the rough endoplasmic reticulum
Protein synthesis
Describe the structure of the smooth endoplasmic reticulum
Highly folded membrane
What is the function of the smooth endoplasmic reticulum
Lipid synthesis
Proteases and stored synthesised proteins
Describe the structure of a ribosome
2 subunits attached together
Attached to rough endoplasmic reticulum
What is the function of the ribosomes
Large catalyst
Translates genetic code into chains of amino acids
Deposits the protein into the endoplasmic reticulum
What happens in the cytoplasm
Site of glycolysis
What are the 3 components of cytoplasm
Cytoskeleton with associated motor proteins
Organelles with other multi protein complexes
Cytoplasmic inclusions and dissolved solutes
What is cytoplasm
It is the fluid that fills the cell but isn’t in the nucleus
What are vesicles and what are there functions
Vesicles are spherical membrane bound organelles which are able to transport and store materials and exchange between different compartments
Examples of vesicles- cell surface derived, Golgi-derived
What is the function of the vacuole
Hold various solutions or materials
What is a vacuole
Chamber surrounded by a membrane which is semi-permeable so only lets certain molecules in and out
Where is the nucleolus found
In the nucleus
What is the function of the nucleolus
Site of DNA transcription
Forms ribosomal RNA
Describe the structure of a plasma membrane
Double layer of lipids with hydrophobic head and hydrophilic tail
Contains proteins and lipids
What are the functions of the plasma membrane
Controls passages of molecules
Physical barrier
Selective permeability
Endo/exocytosis
Cell signalling
What are the components of a plasma membrane
Phospholipids
Cholesterol
Membrane proteins
Carbohydrate groups
What makes up a phospholipid
Glycerol
2 fatty acid tails
Phosphate head linked head group
Where do microtubles arise from and what is an example
They arise from centromeres
Example- tubulin
Where are microtubles found
They are found in all cells except red blood cells
What is an example of a micro filament
Actin
What are centrosomes made from
They are made from 2 centrioles
What is the functions of centrosomes
Organise microtubles
Provide structure for the cell
Pull chromatids apart during cell division
Where do lysosomes come from
They are derived from the golgi
What is the function of lysosomes
They contain digestive enzymes
Site of breakdown for most molecules
What are the different types of cell junctions
Tight junctions
Adherens
Desmosomes
Gap junctions
Hemi-Desmosomes
What are tight junctions
They seal neighbouring cells together in an epithelial sheet to stop leakage
What are adherens
Joins an actin bundle in one cell to a similar bundle in another cell
What are demosomes
Join the intermediate filaments in one cell to them of a neighbouring cell
What are gap junctions
Allows passage of small water soluble ions and molecules
What are hemisphere-desmosomes
They anchor intermediate filaments in a cells to the basal lamina
What are endosomes
They are membrane bound vesicular and tubular structures that live between golgi and membrane
What are peroxisomes
They are small membrane bound organelles which contain enzymes which oxidase long chains of fatty acids
What are peroxisomes involved in
They are involved in the process where fatty acid chains are broken down to make ATP
What does the Nucleus contain and what are each individuals function
Nuclear envelope
- made up of 2 layers -outer layer and inner layer
-inner layer = protein lamins which binds to DNA and controls cell division
-outer layer = made up of ribosomes
Nuclear pores
-allows for transportation of ions between the nucleus and the cytoplasm + cytoplasm into the nucleus
Chromatin
-made up of DNA and proteins called histones
-Euchromatin = lightly packed = used in DNA transcription
-hetrochromatin = tightly packed = less accessible for DNA transcription
What is the overall function of the nucleus
Holds DNA for DNA replication
Makes RNA for DNA transcription
Types of RNA
- tRNA
-mRNA
-rRNA
What makes up the endoplasmic reticulum and how do the rough and smooth differ in structure
The endoplasmic reticulum is a filamentous network
The rough endoplasmic reticulum holds ribosomes on it membrane whereas the smooth doesn’t
What are the main overall functions of the rough endoplasmic reticulum
- Site of protein synthesis mainly for proteins that go into lysosomes, membranous proteins and excretory proteins
- Site of protein folding
- Site of glycosylation = adding a sugar molecule onto the protein through N-type(addition of the sugar onto a nitrogen atom)
What is the overall function of the smooth endoplasmic reticulum
- Site of lipid synthesis of mainly fatty acids, phospholipids and cholesterol
- Site of CYP450 enzymes to perform bio transformation of foreign substances like drugs, alcohol and toxins
- Site of Glucose-6-phosphate metabolism
- Contain sarcoplasmic reticulum which stores large amounts of calcium which is released when needed
What id the different names for the ends of the Golgi apparatus and what are there individual functions
The cis-face is the start of the Golgi apparatus and this is where the vesicles from the smooth and rough endoplasmic reticulum enter
The trans-face is where budding happens at the end of the Golgi apparatus
What are the overall functions of the Golgi apparatus
- receive vesicles of molecules from the smooth and rough endoplasmic reticulum
- They can modify proteins through both N-type and o-type glycosylation and also phosphorylate proteins
- packages molecules
What are the major components of the plasma membrane and what are there individual functions
- Phospholipid bilayer, made up of phospholipid heads which are polar/hydrophobic so they can interact with water and the fatty acid tails which are non-polar/hydrophobic so they cannot interact with water
-Cholesterol, which comes from the smooth endoplasmic reticulum which controls the fluidity of the membrane - proteins both integral and peripheral proteins
What is the overall function of the plasma membrane and what are the different type of movement
It is a selectively permeable barrier to aid with the different type of transportation into and out of the cell
Simple diffusion
Facilitated diffusion
Vesicular transport
What do the lysosomes contain
They contain hydrologic enzymes
Proteases
Nucleases
Lipases
Glucosidases
What are the overall functions of the lysosomes
- breakdown of macromolecules
- Autophagy of dead organelles
- Autolysis of damaged cells
What enzymes do peroxisomes contain
Catalase
Oxidase
Metabolic enzymes
What are the overall functions of peroxisomes
- Turn hydrogen peroxide into water and oxygen through catalase
- Fatty acid oxidation = alpha- branch chain, beta- long chain to make Acetyl CoA
- Make lipids and cholesterol = make plasmalogen which is an important lipid for myelin and white matter of the brain
- Alcohol metabolism through catalase
What are the components of the mitochondria
Outer membrane - smooth and high permeable
Inner membrane- folded, Cristae and less permeable
Mitochondrial matrix- holds mitochondrial DNA
What are the overall functions of the mitochondria
- ATP synthesis via electron transport chain and oxidative phosphorylation
- Metabolic reactions including kerbs cycle, heme synthesis, urea cycle, gluconeogensis, ketogenesis
- Mitochondrial DNA from the mother helps to make proteins for metabolic reactions
What are ribsomes made up of and what is there structure
Ribosomes are made up of 2 subunits the large subunit and the small subunit
They are composed of rRNA and proteins
Where can ribosomes be found
They can be found bound to the membrane of the rough endoplasmic reticulum and in the cytosol
What is the overall function of the ribosome
- site of protein synthesis
Where is the cytoskeleton found
The cytoskeleton is found scatter throughout the entire cell
What are the 3 components of the cytoskeleton
Microfilaments
Intermediate filaments
Microtubles
What are microfilaments made up of and what is there overall functions
The microfilaments are made up of actin
- muscle contraction when bound with myosin
- cytokenesis in cell division as it cleaves the cell into 2 daughter cells
- allows for shape change of white blood cells to perform diapodesis
- aids with phagocytosis on white blood cells by making pseudopods
What are the overall functions of intermediate filaments
- Anchor’s cells to the extracellular matrix
- Anchor’s cells to adjacent cells
- Anchor’s the organelles within the cell
What are microtubles made up of
Microtubles consist of 2 proteins
- alpha-tubulin
- beta-tubulin
Each microtubule contains 13 filaments
What are the overall functions of the microtubles
- intracellular transport via the use of transport proteins dynein and kinesin which is ATP dependant
- used in the metaphase of cell division to pull the chromosomes apart to become sister chromatids
- make up cell extensions like cilia and flagella
