2.1* Flashcards
Name all the parts of a animal cell.
Smooth and rough endoplasmic reticulum, lysosome, Ribosomes, Centrioles, Micro tubules, Nucleus, nucleolus, nuclear membrane, Mitochondria, Golgi apparatus, Plasma membrane.
Name the parts of a plant cell.
Nucleus, tonoplast, cell membrane (plasma), free ribosomes, cell wall (cellulose), SER, RER, chloroplast, mitochondrion, cytosine, Golgi Body, vacuole, nuclear envelope, amyloplast containing starch.
Describe the structure of the nucleus.
The nucleus is the largest organelle. When stained, it shows darkened patches known as chromatin. It is surrounded by a nuclear envelope. This is a structure made of two membranes with fluid between them. A lot of holes, called nuclear pores, go right through the envelope. These holes are large enough for relatively large molecules to pass through. There is dense, spherical structure, called the nucleolus, inside the nucleus.
What is the function of the nucleus?
The nucleus houses nearly all of the cells organic material. The chromatin consists of DNA and proteins. It has instructions for making proteins. Some of these proteins regulate the cells activities. When cells divide, chromatin condenses into visible chromosomes. The nucleolus makes RNA and ribosomes. These pass into the cytoplasm and proteins are assembled at them.
When a nucleus is stained what are the darkens patches known as?
Chromatin
What are the holes in the the envelope of a nucleolus called?
Nuclear pores.
What is the nucleolus?
A dark spherical structure inside the nucleus.
What does the chromatin consist of inside the nucleus?
DNA and proteins
What does the nucleolus make?
RNA and ribosomes
What is the structure of endoplasmic reticulum?
ER consists of a series of flattened, membrane-bound sacs called cisternae.
They are continuous with the outer nuclear membrane. Rough endoplasmic reticulum is studded with ribosomes. Smooth endoplasmic reticulum does not have ribosomes.
What is the function of rough endoplasmic reticulum?
Rough endoplasmic reticulum provides a large surface area for ribosomes which assemble amino acids into proteins. These proteins will actively pass through the membrane into cisternae and are actively transported to the Golgi apparatus. Some of these proteins may be secreted from the cell surface membrane.
What is the structure of a Golgi apparatus ?
A stack of membrane-bound, flattens sacs.
It looks like a pile of pancakes
What is the shape of mitochondria or a singular mitochondrion.
They may be spherical, rod shaped or branched. and are 2-5 um long.
What is chromatin?
Chromatin is genetic material, consisting of DNA wound around histone proteins.
What happens to the chromatin in the nucleus when the cell divides
The chromatin condenses and coils tightly into chromosomes. These make up nearly all the organisms genome.
How do prokaryotic cells divide?
Binary fission and not mitosis
Describe what happens before division in binary fission.
They do not have linear chromosomes, so could not carry out mitosis. However, before they divide, their DNA is copied so that each cell receives the large loop of DNA and smaller plasmids.
Do prokaryotes contain membrane-bound organelles?
Prokaryotes do not have any membrane bound organelles, but they do have organelles that are not covered by a membrane, such as ribosomes.
What are bacteria and micro-organisms?
Bacteria are micro-organisms because they are very small. They are also prokaryotes because of their cell structure. However, not all micro-organisms are prokaryotes. Yeast (which is a single celled fungus) and amoebae have eukaryotic cells.
Explain a viruses cells.
Viruses are microscopic but they do not have cells.
What is the job of the nuclear envelope?
It separates the contents of the nucleus with the rest of the cell.
How does mRNA leave the nucleus?
Through the pores.
What are 4 purposes of the nucleus?
To control the centre of the cell.
Stores the organisms genome.
Transmits genetic information.
Provides the instructions for protein synthesis.
What type of system is rough endoplasmic reticulum?
It is the Intracellular support system.
What is the structure of Smooth endoplasmic reticulum?
There is a system of membranes, containing fluid-filled cavities (cisternae) that are continuous with the nuclear membrane.
There are no ribosomes on its surface.
What is the function of smooth endoplasmic reticulum?
SER contains enzymes that catalyse reactions involved with lipid metabolism, such as;
synthesis of cholesterol
synthesis of lipids/phospholipids needed by the cell.
synthesis of steroid hormones.
It is involved with absorption, synthesis and transport of lipids (from the gut).
What brings materials to the Golgi apparatus?
Vesicles.
How are proteins modified in the Golgi apparatus.
Adding sugar molecules to make glycoproteins.
Adding lipid ,molecules to make lipoproteins.
Being folded into their 3D shape.
In the Golgi apparatus what happens after the protein is packaged into a vessel?
It is stored in a cell or
Moved to the plasma membrane, either to be incorporated into the plasma membrane, or exported outside the cell.
What is the structure of a mitochondrion?
They are surrounded by two membranes with a fluid filed space between them. the inner membrane is highly folded into a cristae.
The inner part of a mitochondrion is a fluid filled matrix.
What is the function of the mitochondria?
Mitochondria are the site of ATP production during aerobic respiration.
They are self replacing, so more can be made if the cells energy needs increase.
They are abundant in cells where much metabolic activity takes place, for example in liver cells and at synapses between neurons where neurotransmitter is synthesised and released.
What is the size and where are chloroplasts found?
They are large organelles 4-10 um long.
They are found only in plant cells and some in protoctists.
What is the structure of a chloroplast?
They are surrounded by a double membrane or envelope.
The inner membrane with stacks of flattened membrane sacks called thylakoids (resembling stacked discs) which contain chlorophyll. Each stack or pile of thylakoids called a granum (plural; grana). The fluid filled matrix is called the stoma.
In a chloroplast what is each stack or pile of thylakoids called?
A granum (plural; grana).
What do chloroplasts also contain that isn’t for photosynthesising.
Loops of DNA and starch grains.
What is the purpose of Chloroplasts?
They are the site of photosynthesis.
What happens at the first stage of photosynthesis?
Light energy is trapped by the chlorophyll and used to make ATP, occurs in the grana. water is also split to supply hydrogen ions.
What happens in the second stage of photosynthesis?
Hydrogen reduces carbon dioxide, using energy from ATP, to make carbohydrates, occurs in the stoma.
Where do you find chloroplasts?
Chloroplasts are abundant in leaf cells, particularly the palisade mesophyll layer.
What is the structure of the vacuole?
The vacuole is surrounded by membrane called the tonoplast, and contains fluid.
What cells contain a vacuole?
Only plant cells have a large permanent vacuoles.
How does a vacuole maintain cell stability?
It is filled with water and solutes and maintains cell stability because when full it pushes against the cell wall, making the cell turgid.
Why do cells need to be turgid?
If all the plant cells are turgid then this helps to support plant, especially in non woody plants.
What does a lysosome contain?
Powerful hydrolytic (digestive) enzymes.
Where are lysosomes most abundant?
They are abundant in phagocytic cells such as neutrophils and macrophages (types of white blood cell) that can ingest and digest invading pathogens such as bacteria.
What is the structure of a lysosome?
They are small bags, formed by the Golgi apparatus. Each is surrounded by a single membrane.
What is the structure of cilia and undulipodia?
These are protrusions from the cell and are surrounded by the cell surface membrane.
Each contains microtubules.
They are formed from centrioles.
What is the function of lysosomes?
Lysosomes keep the powerful hydrolytic enzymes separate from the rest of the cell.
Lysosomes can engulf old cell organelles and foreign matter, digest them and return the digested components to the cell for reuse.
What is the function of cilia.
The epithelial cells lining the airways each have millions of cilia that beat and move the body of mucus.
Nearly all cell types in the body have one cilium that acts as an antenna. It contains receptors that allows the cell to detect signals about its immediate environment.
What is the function of undulipodia?
The only type of human cell to have an undulipodium (a longer cilium) is a spermatozoon. The undulipodium enables the spermatozoon to move.
What organelles do not contain membranes.
Ribosomes, centrioles, cytoskeleton, cellulose cell wall.
What is the structure of a ribosome?
They are a small spherical organelles, about 20 nm in diameter.
Made of ribosomal RNA.
Made in the nucleolus, as two separate subunits, which pass through the nuclear envelope into the cell and cytoplasm and then combine.
Some remain free in the cytoplasm ans some attach to the endoplasmic reticulum.
What is the function of a ribosome?
Ribosomes bound to the exterior or RER are mainly for synthesising proteins that will be exported outside the cell.
Ribosome’s that are free in the cytoplasm, either singly or in clusters, are primarily the site of assembly of proteins that will be used inside the cell.
What is the structure of centrioles?
The centrioles consist of two bundles of micro-tubules at right angles to each other.
The microtubules are made of tubulin protein subunits, and are arranged to form a cylinder.
Before a cell divides, what is the purpose of the necessary organelle?
Before a cell divides, the spindle, made of threads of tubulin, forms from the centrioles.
chromosomes attach to the middle part of the spindle and motor proteins walk along tubulin threads, pulling the chromosomes to opposite ends of the cell.
What is a function of centrioles apart from cell division?
Centrioles are involved in the formation of cilia and undulipodia.
Before the cilia form, the centrioles multiply and line up beneath the cell surface membrane.
Microtubules then sprout outwards from each centriole, forming a cilium or undulipodium.
Where are centrioles not found?
Centrioles are usually absent from cells of (higher) plants but may be present in some unicellular green algae, such as chlamydomonas.
What is the structure of a cycoskeleton?
A network protein structures within the cytoplasm consists of,
Rod-like micro-filaments made of subunits of the protein actin; they are polymers of actin and each micro-filament is about 7 nm in diameter.
Intermediate filaments about 10 nm in diameter
straight, cylindrical microtubules, made of protein subunits called tubulin; about 18-30 nm in diameter.
Give some information on cytoskeletal motor proteins.
The cytoskeletal motor proteins, myosins, kinesins and dyneins are molecular motors. The are also enzymes and have a site that binds to and allows hydrolysis of ATP as their energy source.
What is the function of the microfilaments in the cytoskeleton?
The protein microfilaments within the cytoplasm give support and mechanical strength, keep the cells shape stable and allow the cell movement.
What is the function of microtubules in the cytoskeleton?
Microtubules also provide shape and support to cells, and help substances and organelles to move through the cytoplasm within a cell.
They form a track along which motor proteins (dynein and kinesin) walk and drag organelles from one part of the cell to another.
They form the spindal before the cell divides. These spindal threads enable chromosomes to be moved within the cell.
Microtubules also make up the cilia, undulipodia and centrioles.
What is the function of intermediate filaments in a cytoskeleton?
Intermediate filaments are made of a variety of proteins. They anchor the nucleus within the cytoplasm.
Extend between cells in some tissues, between special junctions, enabling cell-cell signalling and allowing cells to adhere to basement membrane, therefore stabilising tissues.
What is the structure of a cellulose cell wall.
The cell wall of plants is on the outside of the plasma membrane. Is it made from bundles of cellulose fibres.
What is the function of a cellulose cell wall?
Absent from animal cells the cell wall is strong and can prevent plant cells from bursting when turgid.
The cell walls of plant cells,
Provides strength and support, maintains the cells shape, contribute to the strength and support of the whole plant, are permeable and allow solutions (solute and solvent) to pass through.
Fungi have cell walls that contain chitin, not cellulose.
In what ways are prokaryotic cells similar to eukaryotic cells?
They both contain , a plasma membrane a cytoplasm ribosome's for assembling amino acids into proteins DNA and RNA
What is the size difference between prokaryotic and eukaryotic cells?
Eukaryotic cells are much larger.
How does the mechanical strength of prokaryotic and eukaryotic cells compare?
Prokaryotic cells have a much less well-developed cytoskelaton with no centrioles.
What is the main difference in the storage of DNA between prokaryotic and eukaryotic cells?
Prokaryotic cells do not have a nucleus.
Which collection of organelles do prokaryotic cells not contain?
prokaryotic cells do not contain membrane bound organelles such as mitochondria, endoplasmic reticulum, chloroplasts or the Golgi apparatus.
What do cells walls consist of in prokaryotic and eukaryotic cells?
Prokaryotic cells have cell walls made of peptidoglycan whereas eukaryotic cells never have peptidoglycan cell walls.
How is DNA stored in prokaryotic cells?
Prokaryotic cells contain naked DNA that is not wound around histone proteins but floats free in the cytoplasm, as a loop (not linear chromosomes)
What do prokaryotic cells contain that eukaryotic cells do not?
A protective waxy capsule surrounding their cell wall.
Small loops of DNA called plasmids, as well as the main large loop of DNA.
Flagella - long whip like projections that enable them to move. The structure of these flagella differs from that of eukaryotic undulipodia.
Pili - smaller hair like projections that enable the bacteria to adhere to host cells or to each other, and allow the passage of a plasmid DNA from one cell to another.
What is the first step of making and secreting a protein?
The gene that has the coded instructions for a protein such as insulin, housed on chromatin in the nucleus, is transcribed into a length of RNA, called messenger RNA (mRNA).
