Cells 3.2 Flashcards
What are cell walls in fungal cells made out of?
Chitin.
What type of cells can be unicellular and multiclellular?
Algal and Fungal.
What is stored in the nucleus which can be used to create chromosomes?
Chromatin.
What is a tissue?
A collection of similar cells.
What is an organ?
A group of different tissues.
What is an organ system?
A group of organs.
What is the cell-surface membrane made up of?
Lipids and proteins.
What is the function of the cell-surface membrane?
To regulate the movement of substances in and out of the cell as well a having receptor molecules which allows for it to respond to chemicals.
What is the largest organelle?
The nucleus.
What does the nucleus contain?
Chromosomes.
What is the function of the nucleus?
It controls the cellular activity, contains intructions to make proteins and the pores allow mRNA to move between the nucleus and cytoplasm.
What does the nucleolus make?
Ribosomes.
What is the nucleolus?
A dense area of DNA inside of the nucleus which is involved in the production of ribosomes.
What is the function of the mitochondria?
Aerobic respiration, it produces ATP.
Describe the structure of mitochondria.
It has a double membrane, the inner membrane is folded to form cristae and it is coatd in enzymes. There is also the matrix inside which conains enzymes for respiration.
What is the function of chloroplast?
Photosynthesis.
Describe the structure of the chloroplast.
It is small and flattened, surrounded by a double membrane, it has grana, lamellae and is filled with stroma.
What is stroma?
A thick liquid.
What links together the grana?
The lamellae.
What is stacked to make grana?
Thylakoids.
What are thylakoids?
Membranes inside the chloroplast.
What is the plural of granum?
Grana.
What is the plural of lamella?
Lamellae.
What is the function of the golgi apparatus?
To process and package new lipids and proteins as well as making lysosomes.
Describe the golgi apparatus.
It is fluid-filled membrane-bound flattened sacs that recieves vesicles with protein from the RER.
What is the function of the golgi vesicle?
It stores lipids and proteins and transports lipids and proteins, it transports them out of the cell through the cell surface membrane.
Describe the golgi vesicle.
It is a sall fluid filled sac in the cytoplasm which is surrounded by a membrane.
What is the function of the lysosomes?
It contains digestive enzymes and they digest invadinf cells as well as recycling worn out cell components.
What is the enzyme contained in lysosomes?
Lysozymes.
Describe the lysosomes.
It is a round organelle surounded by a membrane with no clear internal structure which is created by the golgi body.
What is the function of the ribosomes?
Protein synthesis.
Describe the ribosomes.
It is a very small organelle which is made up of proteins and RNA which is not surrounded by a membran.
What is the function of the RER?
It folds and processes proteins made by ribosomes.
What does RER stand for?
Rough endoplasmic reticulum.
Describe the RER.
It is a system of membranes which enclose a fluid filled soace, many folds in te membrane give a large surface area and the surface is covered in ribosomes.
What does SER stand for?
Smooth endoplasmic reticulum.
What is the function of the SER?
It synthesizes and processes lipids.
Describe the SER.
It is the same as the RER but does not have any ribosomes.
What is the function of the cell wall?
To support the cell and keep its shape.
Describe the cell wall.
It is made of cellulose in plants and algae, chitin in fungi. There are proes within th walls which connect two cells together by their cytoplasm.
What are the pores within the cell walls called?
Plasmodesmata.
What do the plasmodesmata do?
This connect two cells together by their cytoplam which allows for exchange and transport of substances.
What is the function of the cell vacuole?
It keeps the cell turgid along with its rigid shape, it also stops the plants from wilting.
Describe the cell vacuole.
It contains cell sap and is surrounded by tonoplast.
What is the tonoplast?
The surrounding membrane of the cell vacuole.
Give two functions of the cell-surface membrane.
To regulate movement of substances into and out of the cell and to respond to chemicals like hormones.
What is a capsule made up of?
Secreted slime.
What does the capsule do?
Helps to protect bacteria fro attack by cells of the immune system.
What are plasmids?
Small loopds of DNA that are not part of the main circular DNA molecule.
What do plasmids contain?
Genes for antibiotic resistance which are able to pass between prokaryotes.
What are the two typs of microscopes?`
Light and electron.
What is magnification?
How much bigger the image is compared to the specimen.
What is resolution?
How well the microscope distinguishes between two points that are close together.
What does TEM stand for?
Transmission electron microscope.
What is the advantage of TEM?
It give a high resolution image so it shows small objects.
What are disadvantages of TEMs?
They can only be used on thin, non-living specimen.
What does SEM stand for?
Scanning electron microscope.
What are advanatges of SEM?
They can be used on thick specimen and can be 3D.
What are disadvantages of SEM?
They giver lower resolution images than TEM and can only be used on non-living specimen.
What are the three stages of cell fractionation?
Homogenisation, filtration and ultracentrifugaion.
What is homogenisation?
It is the vibrating / grinding of cells in a blended in order to break up the plasma membrane and release the organelles into the isotonic solution.
What temperature must the solution in homogenisaton be?
Ice-cold.
Why must the solution in homogenisation be ice cold?
In order to reduce the activity of ezmes which break down organelles.
What does isotonic solution mean?
That the soluton should have the same concentration of chemicals as the cell to prevent damage to the organelles via osmosis.
Why must the solution in homogenisation be buffered?
In order to maintain a constant pH.
Describe the filtration stage of cell fractionation.
The homogenised cell solution is filtered through gauze in order to seperate large debris from organelles.
Describe the ultracentrifugation stage of cell fractionation.
The cell fragments are placed into a tube and placed in a centrifuge on a low speed, this causes the heaviest organelles to go to the bottom and form a thick sediment. The lifhtr organells stay supsneded in the fluid above. This is drained into a new tube and the process is repeated but at a higher speed.
What is the pellet in ultracentrifugation?
This is where the heavy organelles go to the bottom and form a thick sediment.
What is the supernatant in ultracentrifugation?
This is where the lighter organelles stay suspended in the fluid above the pellet.
What is heavier the nucleus or chloroplasts?
Nucleus.
What is heavier the mitochondria or chloroplasts?
The chloroplasts.
What is heavier the lysosomes or mitochondria?
The mitochondria.
What is heavier the lysosomes or the endoplasmic reticulum?
The lysosomes.
What is heavier the ribosomes of the endoplasmic reticulum?
The endplasmic reticulum.
What is mitosis used for?
Growth, repair and asexual reproduction.
When does the cell cycle start?
When a cell has been produced by cell division.
When does the cell cycle end?
When the cell divides to produce two daughter cells.
What is a chromosome?
Condensed mass of DNA which appears just before cell division.
Each chromosome is one super-coiled DNA molecule containing 1000s of genes.
What is a chromatid?
One half of a double chromosome (present at the start of cell division).
What is a centromere?
The point of attachment of two chromatids on a double chromosome.
What is a centriole?
Bundles of protein fibres, found near the nucleus. Centrioles migrate to opposite poles of the cell during mitosis and form the spindle.
What is cytokinesis?
Division of the cytoplasm to produce two new cells.
What does a chromosome consist of?
Two strands called sister chromatids which are joined in the middle by a centromere.
What does each sister chromatid on a chromosome contain?
Identical genetic information so that each daughter cell also contains identical genetic information.
What happens during interphase?
During interphase the cell
carries out normal functions, but also prepares to divide. The
cells DNA is unravelled and
replicated. The organelles
are also replicated. ATP
content is increased.
What happens during prophase?
Chromosomes condense.
Centrioles move to opposite
ends of the cell, forming a
network of protein spindle
fibres.
Nuclear envelope begins to
break down so chromosomes lie
free in the cytoplasm.
Nucleolus is no longer visible.
What is a centrosome?
An organelle that consists of two centrioles. A centriole is a structure made of microtubuel proteins arranged in a particular way.
What happens during metaphase?
Chromosomes align in the
equator of the cell.
Each chromosome is attached
to a spindle fibre by its
centromere.
One chromatid from each
chromosome is attached, by
the microtubules, to each pole.
What happens during anaphase?
Centromere of each
chromosome divides, separating
each pair of sister chromatids.
Spindle fibres contact, pulling
chromatids to opposite poles.
(V-shaped)
Cytokinesis starts
What happens during telophase?
Chromatids reach the poles and
uncoil to become long and thin (now called chromosomes again).
Nuclear envelope forms around each group of chromosomes – now have 2 nuclei.
Spindle fibres break down.
Cytokinesis finishes
What is the mitotic index?
The mitotic index is the proportion of cells in a tissue sample that are undergoing mitosis. It lets you work out how quickly the tissue is growing.
What is the equation for mitotic index?
Mitotic index = number of cells with visible chromosomes / total number of cells observed.
