Chapter 3- Cells Flashcards
What is the role of the nuclear envelope
The nuclear envelope controls the entry and exit of materials in and out of the cell. The outer layer has endoplasmic reticulum and ribosomes on its surface
What is the role of nuclear pores
Nuclear pores allow a passage for large molecules e.g ribosomal RNA
What is the role of mitochondria
Mitochondria are the sites for aerobic respiration therefore responsible for the production of ATP.
What are cristae and explain their functions
Cristae are extensions of the inner membrane this increases surface area for attachment of enzymes and other proteins
What is a matrix and explain its function
Contains lipids, proteins, ribosomes and DNA. Matrix allows the mitochondria to control the production of own proteins
Where would more mitochondria be found and why
More mitochondria would be found in cells with a high metabolic rate as the mitochondria is responsible for the production of ATP
What are the roles of mitosis
Mitosis is used for growth
Repair and reproduction
What happens in the stage Prophase
Chromosomes become visible.
Chromosomes are drawn towards equator of the cell.
Nucleus disappears.
Nuclear envelope breaks open.
What happens in the stage telophase
Chromosomes reach poles and become longer and thinner.
Spindle fibres disintegrate
Nucleus and nuclear envelope reforms.
Cytoplasm divides in cytokinesis.
What happens in metaphase
Chromosomes alone up on the centre of the cell and spindle forms.
What happens in the stage of anaphase
Spindle fibre attach to chromatids contract.
Chromatids are pulled towards poles.
What happens in interphase
Chromosomes are invisible and replication of DNA
What are the strengths of a transmitter electron microscope (TEM)
Shorter wavelengths allows more focused images.
Better magnification.
High resolving power.
What are strengths of scanning electron microscope. (SEM)
A thin specimen is not needed.
Able to produce a 3D image.
High resolving power.
What are the weaknesses of a Scanning electron microscope (SEM)
A complex staining process is needed.
Artefacts may appear on the photo micrograph.
Must be in a vacuum.
What are the weaknesses of a Transmitter electron microscope (TEM)
Not in colour.
Complex staining process needed. Living organisms can’t be observed.
Thin specimen needed resulting in a 2D image.
Artefacts May appear on photomicrograph.
What is the role of the cytoplasm
The cytoplasm allows substances to pass into and out of the cell.
What do chloroplasts do
Chloroplasts carry out photosynthesis.
What are the role the Golgi body.
They add carbohydrates to form glycoproteins. They also produce secretory enzymes and form lysosomes.
What are the roles of lysosomes
Lysosomes break down cells by exocytosis.
What does the rough endoplasmic reticulum (RER) do
Provides a large surface area for the synthesis of proteins and provides a pathway for transport of materials.
What is the role of the smooth endoplasmic reticulum (SER).
Synthesis of lipids. Stores and transports carbohydrates.
Explain differences between a prokaryotic cell and a eukaryotic cell.
A prokaryote doesn’t have a true nucleus.
Prokaryotes have DNA in the form of a plasmid.
Prokaryotes have no membrane bound organelles.
Prokaryotes have no chloroplasts.
Eukaryotes have larger ribosomes (80S)
Eukaryotes don’t have a capsule.
Explain the process of cell fractionation.
Tissue is placed in a cold, buffered solution which has the same water potential.
Then tissue goes through homogenisation.
Then goes through ultracentrifugation.
Why are tissues placed in a cold solution
This reduces enzyme activity.
What is the reason for tissues being placed in a solution of the same water potential
To prevent from bursting or shrinking due to osmotic gain or loss of water.
Why is the solution which the tissue is placed in buffered.
So that the pH does not fluctuate.
Explain the process of ultracentrifugation.
The tube of homogenate is spun at a slow speed.
Heaviest organelles are forced to the bottom of the tube forming a pellet.
The supermarket is removed and transferred to be spun at a faster speed.
2nd heaviest organelles forced to bottom forming pellet
Process continued with an increase in speed each time.
What is the formula for magnification.
Magnification=
size of image/size of real object.
Formula for size of real object.
Size of real object=
Size of image/magnification
