Studied by 3 peopleDefine organelles
Components of cells which perform a specific function
Define ultrastructure
The internal structure of a cell
Whats the largest organelle in the cell
The nucleus
What organelle stores DNA
Nucleus
What are the three main functions of the nucleus
Store and transmit genetic info. Provide mRNA for protein synthesis. Act as the control centre of the cell
How is the nucleus separated from the rest of the cell
Presence of the nuclear envelope
What is the nuclear envelope composed of
A double membrane containing nuclear pores
What do the nuclear pores allow
Allow substances to pass through, like mRNA, ribosomes and some hormones like steroid
Whats contained in the nucleoli
Densley packed DNA and protein
Where is ribosomal RNA made
Nucleolus
Where are ribosomes assembled
Nucleolus
How is chromatin formed
DNA being tightly packaged through association with histone proteins
What is chromatin and where is it found
Nucleus. It's genetic material and condenses into tightly coiled chromosomes
How does the nucleus control all the cells activities
By controlling the transcription of DNA
Whats the cytoplasm in the nucleus called
Nucleoplasm
How big are ribosomes
20nm wide
Do ribosomes contain a membrane
No
What are the two subunits that make up ribosomes
40s (smaller) and 60s (bigger) subunits
What is each subunit of ribosomes made out of
Ribosomal RNA and protein
Where can ribosomes be found
On the R.E.R or free floating in cytoplasm
Whats the function of the ribosomes bound to the rough endoplasmic reticulum
Synthesise proteins to be exported out of the cell
Whats the function of free floating ribosomes
Synthesise proteins that will be used inside the cell
Whats the function of the mitochondria
Carry out aerobic stages of respiration to produce ATP
Whats the function of the membrane of the mitochondria
Controls what enters and exits the mitochondrion
Whats the purpose of the cristae
Increase SA for attachment of proteins involved in aerobic respiration
What does the matrix contain
Enzymes for aerobic respiration, lipids, ribsomones and DNA
Whats the function of mitochondrial ribosomes and mitochondrial DNA
Allow the mitochondria to self replicate in response to increased energy demand
What is the cell surface membrane composed of
Two layers of phospholipids (phospholipid bilayer)
Whats the essential role of the cell surface membrane
Controls what enters and exits the cell
What does the cell surface membrane have on it
Receptors to interact with other proteins and respond to chemicals like hormones
What does the cytoplasm contain
Dissolved molecules that take part in metabolic reactions
What is the cytoskeleton
Complex network of proteins in the cytoplasm
Whats the function of the cytoskeleton
Give the cell mechanical strength and involved with movement of organelles in the cell
What are the three components of the cytoskeleton
Microfilaments, intermediate filaments and microtubules
Whats the smallest component of the cytoskeleton
Microfilaments
How big are microfilaments
7nm
What are microfilaments made of
Actin
What is actin
A polypeptide that makes up microfilaments
Whats the functions of the microfilaments
The mesh in cytoplasm is important for maintaining shape and mechanical strength and important for cell movement in cells like amoebas and lymphocytes
Whats the second smallest component of the cytoskeleton
Intermediate filaments
How big are intermediate filaments
10nm in diameter
What are intermediate filaments made out of
Interlocking protein fibres
Whats the functions of the intermediate filaments
Anchor the nucleus within the cytoplasm and are able to extend outside the cell, allowing cells to stick together and communicate
What are the largest type of cytoskeleton filament
Microtubules
How big are microtubules
18-30nm in diameter
What are microtubules made out of
Tubulin
What are microtubules important for
Movement of substances and organelles in cytoplasm
How do microtubules carry out their function
Help of dynein and kinesin which walk along the microtubules and carry organelle with them.
What are dynein and kinesin
Cytoskeletal motor proteins
What do motor proteins need to carry out their function
Energy from ATP hydrolysis
What do microtubules compose and why
The spindle for cell division, it enables chromosomes to be moved within the cell
What are centrioles made up of
Microtubules
How is the spindle formed
Long microtubules extend from the centrioles
What are centrioles and microtubules also important for (excl. cell division)
Formation of cilia and undulipodia
What are cilia and undulipodia
Protrusions from cells which are surrounded by a cell membrane
How are cilia and undulipodia formed
Centrioles divide and line up at cell membrane. The microtubules grow outwards which deform the membrane and form protrusions
Whats the difference between cilia and undulipodia
Cilia are shorter
Give and example of cells that have many cilia and why
Epithelial cells lining airways to help mucus move along airways
Why do most cells have at least one cilium
They contain receptors allow the cell to detect signals in environment
Whats the only human cell that contain undulipodia and why
Sperm cells to enable them to move
What type of cells are lysosomes highly abundant in
Secretory cells
Why type of bilayer surrounds lysosomes
Lipid bilayer
Give an example of a lysosome
Vesicles
Where are vesicles formed
Golgi apparatus
What do vesicles contain
Digestive enzymes like proteases, lipases and lysozymes
What is the function of lysozymes
Hydrolyse specific bacterial cell walls
Where are vesicles abundant in
Phagocytic cells
Whats the function of the vesicle
Keep the hydrolytic enzymes in separate compartments
Name some roles of lysosomes
Hydrolysis of material ingested by phagocytic cells. Digestion of old or damaged organelles to recycle useful components. Complete breakdown of cells when they have died. Release of enzymes to digest material outside of cells.
Whats the fluid in the E.R called
Cisternae
Whats the main function of the R.E.R
Provide a large surface area for protein synthesis
Whats the main function of the S.E.R
Synthesise, store and transport lipids and carbohydrates
What does the S.E.R contain many of and why
Enzymes to aid lipid metabolism incl. synthesis of cholesterol and steroid hormones
Whats the function of the golgi
Modifies and repackages proteins, lipids and carbohydrates
How are proteins modified in the Golgi Apparatus
By joining them with other molecules
Give examples of how proteins can be modified
Lipids added to make lipoproteins, sugars added to make glycoproteins and polypeptides can be joined together to make the full protein
What come off the Golgi to form a vesicle
Proteins, carbohydrates and lipids
Where do the vesicles get sent to after budding off the Golgi
Cell surface and other places within the cell for storage
What happens to the vesicles once they reach the cell surface
Used for incorporation into the plasma membrane and secretion or to be exported outside the cell
What is the first stage of protein synthesis
Gene coding for insulin in transcribed into mRNA in the nucleus
What happens after the mRNA is transcribed into the nucleus
It leaves the nucleus through the pores and travels to the ribosomes on the R.E.R
What happens when mRNA reaches the R.E.R
The ribosomes translate the mRNA and assemble insulin molecules, then pass into the cisternae of the R.E.R
What happens when mRNA goes reaches the cisternae of the R.E.R
The vesicles with the insulin are pinched off the R.E.R and travel to the Golgi Apparatus
What helps the vesicles get to the Golgi
Microtubules and motor proteins
What happens when the vesicles get to the Golgi
They fuse together
What happens when the vesicle fuses with the Golgi
The insulin molecule is processed and packaged
What happens when the insulin is packaged and processed
The modified molecules bud off from the Golgi in vesicles
What happens when the vesicles bud off the Golgi
The vesicles travel towards and fuse with the plasma membrane
What happens when the vesicles fuse with the plasma membrane
The plasma membrane opens to release the molecules outside (exocytosis)
How big are chloroplasts
4-10µm
Whats the function of the chloroplast
Site of photosynthesis
Whats the function of the double membrane of the chloroplast
Controls what enters and leaves the chloroplast
What is a granum
A stack of thylakoids
What do thylakoids contain
Chlorophyll
Where does the first stage of photosynthesis take place?
In the chlorophyll
How are the grana linked together
By intergranal lamellae
What is the stroma
Fluid filled chamber surrounding the grana.
Where does the second stage of photosynthesis take place
Stroma
What does the stroma contain and why
Enzymes, starch grains, DNA and ribosomes, allowing chloroplasts to quickly and easily manufacture proteins for photosynthesis
What do plant vacuoles contain
Dissolved solutes
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