(2.1) Cell structure Flashcards
What is the maximum resolution of a light microscope?
0.2 micro metres
Define resolution
The ability of a microscope to distinguish details of a sample or specimen
What is the maximum resolution of an electron microscope?
0.1 nano metres
What is the role of the ribosomes on the RER?
Synthesises proteins that will be exported outside of the cell
What is the function of the RER?
- provides a large surface area of a ribosome
- An intracellular transport system - the cisternae form channels for transporting substances to different areas of the cell
What is the role of the SER?
sight of lipid and steroid synthesis
Describe the structure of the nucleus?
- a nuclear envelope with pores creating a membrane bound organelle
- nucleolus
- nucleus
What is the function of the nucleolus?
- Contains RNA
- Makes ribosomes
How do dissolved substances and ribosomes leave the nucleus?
The outer and inner nuclear membranes fuse together
How do larger substances e.g. mRNA leave the nucleus?
Through the nuclear pores
Where are an organism’s genes stored?
- in chromosomes
- chromatin wrapped in histone proteins
What is the role of the nucleus?
- control centre of the cell
- stores the organism’s genome
- transmits genetic information
- provides instructions for protein synthesis
What is the role of the golgi apparatus?
- receives/modifies proteins
- packages and organises where proteins need to go
How can the golgi apparatus modify proteins?
- adding a sugar
- adding lipid molecules
- being folded into their 3D shape
What are glycoproteins and how are they formed?
When the golgi apparatus modifies a protein by adding a sugar
What are lipoproteins and how are the formed?
When the golgi apparatus modifies a protein by adding a lipid
What is the function of a mitochodria?
The site of aerobic respiration
What is the function of independent ribosomes?
Primarily the site of assembly of proteins to be used outside of the cell
What is the function of centrioles?
- creates spindle (threads of tubulin)
- centrioles multiply/line up beneath the cell surface membrane and microtubules sprout outwards from each centriole to create cilium and undulipodium
What is the role of lysosomes?
Contain enzymes for digestion
What is the purpose of the cell wall?
Structural support so that the cell is resistant to the vacuole pushing against the plasma membrane, otherwise the cell would burst
What is the cell wall permeable to?
Water
What is the function of the chloroplast?
It is the site of photosynthesis
What is the structure of the chloroplast?
- outer membrane
- inner membrane
- intermembrane space
- granum
- thylakoids
- intergranal lamellae
- stroma
What are granum?
Stacks of thylakoids
What is the function of thylakoids?
Where light dependent photosynthesis is carried out, creating chlorophyll
What is the function of the stroma?
Where light independent photosynthesis is carried out with CO2 fixing
What is the function of the amyloplast?
Stores starch
What is the function of the vacuole?
- filled with sap and water
- maintains turgor pressure
- regulates osmosis
What are cisternae?
Fluid filled cavities in the endoplasmic reticulums
What is carried out at the mitochondrial matrix?
- where the krebs cycle takes place
- CO2 is produced
What is carried out at the cristae in the mitochondria?
- Oxidative phosphorylation
- ATP is generated
What are the intermembrane spaces in the chloroplast and mitochondria?
Space between the inner and outer membrane
What are the mitochondrial matrix?
Any liquid space
What do most antibiotics target in bacteria and why?
Target the bacterial cell wall as once it is broken down the bacterium bursts under the osmotic pressure
What are pili?
- Hair like projections on the bacterial cell surface
- Allow cell communication and horizontal gene transfer
What is horizontal gene transfer?
Where bacterium cells interlock pili and can pass genetic information in plasmids
What are plasmids?
Smaller loops of DNA in bacterial cells
Why is horizontal gene transfer prominent when it comes to antibiotic resistance?
The plasmids can be passed which store information about the antibiotics which can cause more of the bacterial cells to become resistant to it
What is different between eukaryotic and prokaryotic cells?
- prokaryotes are smaller
- Naked DNA with no histone proteins
- no nucleus
- no membrane bound organelles
- smaller ribosomes
- flagella vs cilia/undulipodium
What is the difference between flagella and undulipodium?
Flagella are like propellers and undulipodium move like waves
What is the triangle for calculating magnification?
actual | magnification
What is the bacteria cell wall made up of?
Peptidoglycan
What is peptidoglycan a combination of?
Peptides and Carbohydrates
Describe the process of transcription and translation
- A gene moves out through the nuclear pores into the cytoplasm in the form of mRNA
- mRNA binds to ribosomes on the RER and translation occurs
- A new protein is made and packaged by the pinching of cisternae
- The vesicle travels to the golgi apparatus where the protein is modified
- The vesicle is then secreted and travels towards the plasma membrane
- The vesicle fuses with the cells surface membrane and is secreted via exocytosis
