A1 Cells Flashcards
What is the function of the Golgi apparatus?
Modifies proteins
What is the function of the mitochondria?
Release energy/ATP by aerobic respiration
Name the organelle shown on the electron micrograph
Mitochondria
What is the function of the ribosomes?
Protein synthesis
What is the function of the chloroplast?
Photosynthesis
Name the organelle shown on the electronmicrograph
Rough endoplasmic reticulum
Name 2 structures found in the nucleus
Chromosomes and nucleolus/nucleoli
What is the function of the cell membrane?
Controls which substances enter and leave the cell
What is the function of the Golgi vesicles?
Transports chemicals across the Golgi apparatus or to the cell membrane.
What is the function of the lysosome?
Hydrolyses dead or damaged organelles.
What is the function of the rough endoplasmic reticulum?
Makes and transports proteins
What is the function of the smooth endoplasmic reticulum?
Makes and transports steroids
What is the function of the cell wall?
Rigid outer covering to the plant cell. Supports the plant cell.
Name the chemical that makes up the cell wall in plants
Cellulose
Name the two chemical components of murein
Its is a glycoprotein
Protein and carbohydrate
Name the organelle shown on the electronmicrograph
Golgi apparatus
Name the chemical that makes up the cell wall in bacteria
Murein
Name the chemical that makes up the cell wall in fungi
Chitin
What is the function of the vacuole?
Stores cell sap. Keeps the cell turgid.
The epithelium cells of the small intestine have microvilli on them.
What is their function?
Increase surface area for absorption of digested food.
What is a tissue?
A group of similar specialised cells that perform a particular function.
What is an organ?
A group of tissues which perform a particular function
What is a system?
A group of organs which perform a particular function
Which are larger? Prokaryotic cells or eukaryotic cells?
Eukaryotic cells
Give three ways in which prokaryotic cells are different to eukaryotic cells
No membrane-bound organelles eg mitochondria
No nucleus
Smaller ribosomes
Cell wall made of glycoprotein not cellulose
Give 3 features that are found in prokaryotic cells and not eukaryotic cells
One or more plasmids
A capsule surrounding the cell
One or more flagella
Give three features found in viruses
Genetic material
Capsid
Attachment protein
Viruses are acellular. What does this mean?
Not made of cells
Give 2 advantages of using a light microscope rather than an electron microscope
Can see living cells
Cell movement can be observed
Very few artefacts
Can see natural colour
Give two advantages of using an electron microscope rather than a light microscope
Higher resolution
Higher magnification
Why does an electron microscope give better resolution
than a light microscope?
Uses a shorter wavelength of the electromagnetic spectrum
Give an advantage of a scanning electron microscope over a transmission electron microscope
3D images vs 2D images
Observe the surface of a structure
Give an advantage of a transmission electron microscope over a scanning electron microscope
Higher resolution.
Observe internal structures in the cell
Why are cells dead when viewed under an electron microscope?
High energy electrons damage cells
Vacuum needed
Cells dehydrated
What does magnification mean?
How large the image is compared to real life
What does resolution mean?
The smallest distance below which two discrete objects will be seen as one.
What is the formula for calculating magnification?
Magnification = size of image/size of real object
Describe how cell components can be separated in a lab.
Cell fractionation
Homogenate made by using a blender or mortar and pestle.
Filter - to remove cell debris
Centrifuge
Use different speeds to separate components of different density.
How is pH maintained when separating cell components?
Buffer
Why is an isotonic suspension needed when separating cell components?
Prevent osmosis.
Prevent organelles shrinking or bursting
How is enzyme activity reduced when separating cell components?
Ice cold conditions
What is an artefact?
A change in the structure of an organelle during the preparation for observation under an electron microscope.
In which type of cell would the 80S ribosome be found?
Eukaryotic cell
Where would an 70S ribosome be found?
Prokaryotic cell
Mitochondria
Chloroplasts
When observing cells under a microscope why does the specimen need to be thin?
Single layer of cells,
Allows light to pass through
How is a temporary slide prepared for viewing?
Add drop of water to slide
Take a thin (1 cell thick) tissue sample
Place on glass slide (float on water)
Add stain
Lower coverslip onto slide using a mounted needle
Give 3 rules when producing a scientific drawing
No shading
Single lines (no sketching)
Add labels/annotations
No crossed guidelines
Add magnification/scale bar
How could the mean length of a cell be determined using an eye piece graticule?
Place micrometer on stage
Calibrate the graticule using a stage micrometer
Measure length of a random selection of cells using the graticule.
Calculate the mean
Describe the structure of a lysosome
Sac surrounded by a single membrane
Proton pumps maintain acidic conditions
Contains hydrolytic enzymes called lysozyme
Describe the structure of a ribosome
Made of RNA and protein
Free in the cytoplasm or attached to endoplasmic reticulum
Large subunit - joins amino acids
Small subunit - contains mRNA binding site
Describe the structure of rough endoplasmic reticulum
Cisternae - network of tubes and flattened sacs
extends from nuclear membrane to cell membrane
Ribosomes attached to the outer surface
Describe the structure of the plant cell wall
Made of cellulose microfibrils
Pores (plasmodesmata) allow molecules to pass between cells
Describe the structure of the plant vacuole
Surrounded by a single membrane - tonoplast
Contains cell sap - water, mineral ions, enzymes, soluble pigments.
Describe and explain the adaptions shown by an epithelium cell
of the small intestine
Folded membrane (microvilli) increase surface area for diffusion
Many mitochondria - large amount of ATP needed for active transport
State the role of plasmids in prokaryotes
Small rind of DNA that carriers non-essential genes
Can be exchanged between bacteria
State the role of the capsule in prokaryotes
Polysaccharide layer that
Prevents desiccation
Acts as a food reserve
Adhesive
Mechanical protection against phagocytosis
Describe the structure of a viral particle
Linear genetic material (DNA or RNA)
Viral enzymes eg. reverse transcriptase
Surrounded by a capsid (protein coat)
No cytoplasm
Attachment proteins on outer surface
State the role of attachment proteins on viral particles
Enable virus to bind to complementary sites on host cell
Describe how a transition electron microscope works
High energy beam of electrons pass through thin slice of specimen
More dense structures appear darker as they absorb more electrons
Focus image onto fluorescent screen or photographic plate using magnetic lenses
Name the type of microscope used to produce this image of a pollen grain
Transmission electron microscope
Describe how a scanning electron microscope works
Focus beam of electrons onto a specimens surface using electromagnetic lenses
Reflected electrons hit a collecting device and are amplified to produce an image on a photographic plate or fluorescent screen
Describe how an optical microscope works
Lenses focus rays of light and magnify the view of a thin slice of specimen
Different structures absorb different amounts and wavelengths of light
Reflected light is transmitted to the observer via the objective and eyepiece lens
Name the organelle shown on the electronmicrograph
Chloroplast
Name the type of microscope used to produce this electron micrograph
Scanning electron microscope
