Cell Structure Flashcards
What is resolution
Distinguish between 2 points
What is the formula for magnification
Drawn size
_____________
Actually size
Cell fractionation
What does cold do
To reduce enzyme activity that might break down organelles
Cell fractionation
What does isotonic do
Same water potential
So water doesn’t come In or out and prevents organelle from bursting or shrinking through osmosis
Cell fractionation
What does buffered do
Maintains pH levels so it doesn’t fluctuate so proteins don’t denature
What are the 2 stages of cell fractionation
Homogenised
Ultracentrifugation
What does homogenised do
organelles placed into blender and is filtered as while cells or cell debris is removed
What happens in a ultracentrifugation
Fragment is placed into a centrifuge and is spun slowly at a LOW SPEED, so that the HEAVIEST organelles will be forced to the bottom ( nucleus first)
The SUPERNATANT (fluid at top) is removed and then spun at the HIGHER SPEED for LONGER so then the NEXT HEAVIEST organelles forced to the bottom ( MITOCHONDRIA)
Process is repeated at increases SPEED AND TIME
Optical microscope
Uses beams of light through specimen and uses 2 lenses: eyepiece lens and objective lens
Limitation= not much detail produced with low magnification and resolution
Transmission electron microscope (TEM)
Electrons are fired from an electrogun and pass through a thin section of the specimen
Gives high resolution, the electron beam focused using electromagnets and denser parts of the specimen to absorb more electrons (darker parts)
Image produced on a florescent screen
Magnification can be increased up to 500,000 X
Limitation= must be in a vacuum, specimen must be rally thin and the specimen are killed (complex process) and only 2D images are formed and method can have artefacts ( alterations to the specimen)
Scanning electron microscope (SEM)
Electrons are passed across the surface of the specimen
Scattered electrons form and image on the screen
Depressions appear darker and extensions appear lighter
Produces 3D image
Limitations= resolving power is lover then TEM and is less complex than TEM so less chance of an artefact
Cell surface membrane role
Responsible for controlling what goes in and out and sending and receiving chemical signals
Role of the nucleus
2 membranes, nuclear pores that allows stiff to go in and out and contains chromosomes & the chromatin which is everything inside the nucleus and the nucleus - RNA (were ribosomes are made)
Role of the mitochondria
Aerobic respiration = produces ATP
Cristae increases the surface area and ATP synthase the matrix which is the filling in the mitochondria, contains DNA and has its own ribosomes to make its own protein and cells can’t survive without them
Role of the chloroplast (in plants and algae )
Double membrane and stacks of chloroplast is known as granum and chlorophyl embedded in, the stacks can be joined together and thylakoid membranes (covers little rings in the stacks) has own ribosomes and DNA, this is where photosynthesis takes place and has a large surface area
Role of the Golgi apparatus and Golgi vesicles
Modified and packages proteins, carbohydrates and lipids maybe added, leave cell/ stay in cell and a typical lysis me releases Golgi vesicles
Role of the lysosomes
Contains enzymes, hydrolyse/ digest dead organelles or things that enter the body.
A type of Golgi vesicles that realised lysosomes
Role of the ribosome
Protein synthesis, not membrane bound and found in both eukaryotic and pro-kyotic cells
Role of the roughy endoplasmic reticulum (RER)
Protein synthesis as they have ribosomes, cisternae (hallow parts as they are all joined together) and contains fluid (kineted)
Smooth endoplasmic reticulum (SER)
Lipids (triglyceride) and has no ribosomes, lipid synthesis and joined to RER
Role of the cell wall
Cell wall is composed of cellulose, which is a structural carbohydrates and is considered as a complex sugar
The plant cell wall consists of 3 layers
Is known to be a tough, rigid structure and layers that surrounds certain cells
Role of the cell vacuole ( in plants)
Supports herbaceous plants, and herbaceous parts of woody plants by making cells turgid
The sugar and amino acids may acts as a temporary food store and also the pigments may colour petals to attract polo sting insects
Adaptations to eukaryotic cells
Mitochondria
The inner membrane is adapted by becoming a double membrane that is folded to form the extensions (cristae) to have more efficient control over the materials hate enter and exit the organelle
Prokaryotic cells
Are found in bacteria and are much smaller than eukaryotic cells
How do prokaryotic cells differ from eukaryotic cells
Their cytoplasm lacks membrane bound organelles
They have smaller ribosomes (70s)
They have no nucleus but instead have a circular DNA molecule that floats freely in the cytoplasm and doesn’t contain introns (junk)
Cytoplasm isn’t associated with proteins
Cell wall is made of muerin (a glycoprotein) that prevents cells from bursting if too much water is gained from osmosis
What do many prokaryotic cells contain
One or more plasmids (extra DNA) and can be passed from one prokaryotic to another and can code for antibiotics resistances
A slime capsule that surrounds the cell to prevent it from drying out and also can’t be engulfed by a white blood cell
One or more flagella which is used for movement however bacteria doesn’t always have them
Viruses are acellular and non living and the structure of a virus particles include genetic material, capsid and attachment proteins
Capsid = protein Layer that encloses 2 single stand aid RNA and some enzymes
Attachment proteins = are proteins used by virus to identify and attach to host cells
What is magnification
How much bigger the image is
