3.2 Cells Flashcards
Covers following topics: eukaryotic cells and organelles, prokaryotic cells and organelles, analysis of cell components, cell division - mitosis, cell division - investigating mitosis
Name the 10 organelles found in eukaryotic cells.
1) Nucleus
2) Golgi apparatus and golgi vesicles
3) Rough endoplasmic reticulum & Smooth endoplasmic reticulum
4) Ribosomes
5) Mitochondria
6) Cell wall
7) Lysosomes
8) Cell-surface membrane
9) Cell vacuole
10) Chloroplasts
What is the structure of each and what is (one) function of each?
1) Nucleus
- nuceolus
- nuclear envelope
- chromatin
- nuclear pores
Functions: - Controlls the cells activities, contains DNA that has instructures to make proteins.
2) Golgi apparatus and golgi vesicle
- fluid filled membrane bound flattened sacs
Fuctions: Processes and packages new lipids and proteins and makes lysosomes.
Golgi vesicle is membrane bound.
Functions: stores lipids and proteins made by golgi apparatus and transports them out of the cell.
3)RER - system of membrane folds and fluid containing. Lined with ribosomes.
Function: Folds and protein synthesis
SER same no ribsomes
Function: Stores and processes lipids
4) Ribsomes - organelle can be 70s and 80s Function: Site of protein synthesis
5) Mitochondria - inner and outer membrane with crista and matrix.
Function: site of aerobic respiration - very active and requires lots of energy.
6) Cell wall. Rigid structure in plants algae and fungi. In plants, mainly made of cellulose, chitin in fungi.
Functions: supports cells and prevents them from changing shape.
7) Lysosomes - round organelle surrounded by membrane - no clear internal structure. Function: Contains digestive hydrolytic enzymes called lysozymes - break down old or dead organelles.
8) Cell surface membrane - found on surface of animal cells and just inside cell walls of other cells - mainly made of lipids and proteins.
Funtions: Regulates movement of substances into and out of the cell - has receptor molecules - allow to respond to chemicals.
9) Cell Vacuole - found in cytoplasm of plants - contains cell sap, solution of sugars and salts - surrounding membrane called tonoplast. Function: Maintains pressure inside the cell and keeps the cell rigid. Stops plants wilting. Involved in isolation of unwanted chemicals
10) Chloroplast
- flattened structure in plant and algal cells. Surrounded by double membrane and membranes inside called thylakoid membrane. These membranes are stacked up in some parts of the chloroplast to form grana. Grana linked together by lamellae - thin flat pieces of thylakoid membrane. Function: Site where photosynthesis takes place. Some in grana and some in stroma.
What is the structure of prokaryotic cells and Function?
- Cytoplams - no membrane bound organelles. Has ribosomes - but smaller than those in euk,
- Plasma membrane - mainly made of lipids and proteins, controls movement of substances into and out of the cell.
- cell wall supports the cell and prevents it from changing shape. Made from polymer called murein.
- Capsule - made of secreted slime to protect attack by cells of the immune system.
- Plasmids small loops of DNA - can contain genes that provides antibiotic resistance and passed between prokaryotes. Plasmids not always present in prokaryotic cells.
- Circular dna - not membrane bound to histones and one long coild strand.
- Flagellum - one or more for movement.
Are viruses cells? What is the structure of a virus? What do you know about a virus? Write it then look at a textbook and add what you don’t know.
Viruses are just nucleic acids surrounded by protein - not alive and are acellular.
- Smaller than bacteria e.g. HIV about 0.1micrometer.
- No membrane no cytoplasm no ribosomes
- Have core of genetic material as DNA or RNA
- Protein coat around the core called capsid
- Attachment proteins stick out of the edge of the capsid.
4 steps to Replication of prokaryotic cells, what are they? How do Prokaryotes replicate
They replicate by binary fission.
1) Ciruclar DNA and plasmids replicate - main dna only repeated once, plasmids can be many times
2) Cells get bigger and DNA loops move to opposite poles of cell
3) Cytoplasm begins to divide.
4) Cytoplasm divides and 2 daughter cells produced - genetically identical.
How do Viruses replicate?
1) Viruses use attachment proteins to bind to complementary receptor proteins on surface of host cell
2) Not alive, don’t undergo cell division - inject DNA or RNA to host cells. Hijacks own cell machinery to replicate vital proteins e.g. enzymes and ribosomes.
What’s the equation for magnification?
I = AM so M = I ÷ A
What are the 2 main types of microscopes? Give details of both
Optical (light) Microscope:
- Use light to form an image
- max resolution = 0.2 micrometers ( Resolution = How detailed the image is & How well a microscope distinguishes between 2 points that are close together.) Can’t view organelles smaller than 0.2micrometers inc. ribosomes, mitochondria, lysosomes and ER.
Max mag. is about x1500.
Electron microscope:
- uses electrons to form image
- Have higher resolution - more detailed image (Can also see more organelles).
- Have max. resolution of 0.0002 micrometers.
- Max mag. x1 500 000.
What are the 2 types of electron microscopes and how do they work?
TEM:
- Uses electromagnets to foucs a beam of electrons which is then transmitted through the specimen
- dense parts absorb more electrons - appear darker on image
- Good because high resolution images, see internal structure of organelles like chlorplasts
- Used only on thin specimen
SEM:
- Scan beam of electrons across whole specimen. Knocks off electrons from specimen and gathered in cathode ray tube to form image.
- End up to show surface, used to show 3D.
- can be used on thick specimen
- give lower resolution than TEMs
What are the 3 steps to separate organelles? How does ultracentrifugation work? Give some details about them - write what you know, see textbook, don’t know fill in with different colour.
Homogenisation, filtration and ultracentrifugation.
Homogenisation: Done by several different ways e.g. grind blender. To break open plasma membrane and release organelles. Must be ice cold - reduce enzymes that break down organelles. Isotonic - have same water potential prevent osmotic damage. Buffer - prevent enzyme damage and protein damage.
Filtration - remove unbroken cells, tissue debris and large cell debris.
Ultracentrifugation?
- Cell fragments put in tube and spun at low speed - heaviest organelles separate out first like nuclei and flung to bottom to make pellet. Rest of organelles at the top in a fluid called supernatant.
- Supernatant spun at a higher speed. Heaviest organelles form pellet and is removed.
- Repeated until all organelles are removed.
What is mitosis? Why is mitosis necessary? What are the products of mitosis?
Mitosis is when a parent cell divides to form 2 genetically identical cells. Useful for growth and repair. Products are 2 genetically identical daughter cells.
What occurs during the interphase? Give details
Cell carries out normal function - but also prepares to divide. Cell’s DNA is unravelled and replicated to double its genetic content. Organelles also replicated. ATP content increased.
What are the 4 stages of mitosis? Give details of each stage. Create an acronym for the stages.
Acronym
Pet My Alligator’s Tail
Prophase:
- Chromosomes condense, get shorter and fatter - become visible.
- Centrioles start to move to opposite ends of cell
- network of protein fibre called spindles start to form.
- Nuclear envelope breaks down and chromosomes lie free in cytoplasm
Metaphase:
- Chromosomes line up along middle of cell
- Spindles attach to chromosomes by centromere.
Anaphase:
- Centromere divides, separating each chromatids.
- Spindle fibres contract pulling chromatids to opposite poles of the spindle, centromere first.
- makes it appear v shaped.
Telophase: The chromatids reach opposite poles.
- uncoiled and become long and thin - now called chromosomes.
- Nuclear envelope forms around each group of chromosomes so 2 necleui. Cytoplasm divides (cytokinesis) and now 2 daughter cells that’re genetically identical to original cell and to each other. Mitosis is finished and each daughter cell starts the interphase part of the cell cycle to get ready for the next round of mitosis.
What are the 9 steps to prepare a slide?
1) Cut 1cm from tip from growing root - where growth occurs fastest.
2) Prepare boiling tube ad 1M HCl and put in water bath at 60deg.
3) Transfer the root tip into the boiling tube and incubate for 5 mins
4) Use a pipette to rinse the root tip well with cold water. Leave the tip to dry on paper towel.
5) Place the root tip on microscope slide - cut 2mm from the very tip of it - rest get rid.
6) Use unmounted needle to break tip open and spread the cells out thinly.
7) Add few drops of stain and leave or few mins. Stain makes chromosomes easier to see.
8) Place cover slip over cells and push down firmly to squash the tissue - makes tissue thinner allow light through.
Don’t smear the cover slip sideways - damage to chromosomes
9) Look at all stages of mitosis under optical microscope.
What’s the procedure to observe the slide?
- Clip the slide you’ve prepared onto the stage.
- Select the lowest powered objective lens
- Use the course adjustment know to move objective lense down
- Look into eyepiece and adjust focus using fine adjustment knob until see clear image.
- If you need to see the slide with greater magnification swap to higher powered objective lens
