1.1- S1: Cell structure and functioning

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What is the difference between a eukaryote and prokaryote?
Eukaryotes = many cells. prokaryotes = one cell + no membrane bound organelles
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What are plasmodesmata?
are microscopic channels in cell walls of plant cells enabling transport and communication between adjacent cells.
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What is the plasma membrane and what is its function?
Made from lipids and protein. Regulates movement of substances in and out of cells. Receptor molecules= respond to chemicals e.g hormones
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What is the cell wall and what is its function?
Rigid structure around plant cells made from cellulose. Supports the plant cell
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What is the nucleus and what is its function?
large organelle surrounded by nuclear envelope (double membrane) with pores. Chromatin and nucleolus. Holds DNA, pores= movement between nucleus and cytoplasm. nucleolus= ribosomes.
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What is a lysosome and what is its function?
a round organelle surrounded by a membrane- digestive enzymes kept separate from cytoplasm by its membrane. Digests invading cells or breaks down components of cell. e.g sperm penetrating ovum.
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What is a ribosome and what is its function?
Very small organelle either free in cytoplasm or attached to RER. They are the site of proteinsynthesis. mRNA is transported from the nuclear pores and proteins are assembled from amino acids.
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What is the rough endoplasmic reticulum (RER) and what is its function?
membranes enclosing a fluid filled space. Surface covered with ribosomes. It folds and processes proteins assembled by ribosomes.
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What is the smooth endoplasmic reticulum and what is its function?
Has no ribosomes. It synthesises and processes lipids.
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What are vesicles and what are their function?
they are small fluid filled sacs in the cytoplasm, surrounded by a membrane. They transport substances in and out of the cell and between organelles.
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What is the Golgi apparatus and what is its function?
Its a group of fluid filled FLATTENED sacs which processes and packages new lipids to make lysosomes.
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What are mitochondria and what are their function?
oval shaped organelles with a double membrane. The inner one folded forming a structure called cristae. The inside is called the matrix with enzymes for respiration. Site of aerobic respiration producing ATP (adenosine triphosphate.)
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What are chloroplasts and what are their function?
small, flattened structures found in plant cells, surrounded by double membrane. Membranes INSIDE are thylakoid membranes, stacked up to form grana linked by lamellae. Photosynthesis in stroma and grana.
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What are centrioles and what are their function?
small hollow cylinders containing a ring of microtubules. They are involved in separating chromosomes in cell division.
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What are cilia and what are their function?
small hair like structures on plasma membranes of some animal cells. pair of microtubules in the middle and nine pairs in a ring near the outer membrane. Microtubules allow cilia to move which moves substances along the cell surface.
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What are flagella and what are their function?
Like cilia but longer. projecting from cell surface, surrounded by plasma membrane. 2,9 like cilia. Microtubules contract to make flagellum move. They move the cell through substances e.g sperm tail.
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Describe the process of protein production in a cell.
nucleus copies instructions in DNA (e.g for a hormone) into mRNA. mRNA through nuclear pores to ribosomes. Protein synthesised. RER processes proteins. Transported to golgi apparatus by vesicle. further processing. protein enters vesicle -->secretion
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What is the difference between ribosomes on the RER and ribosomes free in the cytoplasm?
RER ribosomes make proteins that are excreted or attached to the cell membrane. Free ribosomes make proteins that remain in the cytoplasm.
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What is the cytoskeleton?
a network of protein threads arranged as microfilaments and mircotubules in eukaryotic cells.
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What are four main functions of the cytoskeleton?
microtubules and microfilaments support the cell's organelles, keep in position. Strengthen cell and maintain shape. Transport of materials e.g chromosomes in cell division. cilia and flagella propel cell-skeletal protein filaments.
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What are differences between eukaryotic cells and prokaryotic cells?
prokaryotic: less than 2 micrometres. Circular DNA. no nucleus. cell wall peptidoglycan. no mitochondria. small ribosomes. Eukaryotic: 10-100 micrometres. Linear DNA. nucleus. larger ribosomes.
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Describe special features of a prokaryotic cell.
mesosome: site of production of ATP. cell wall: made from peptidolycan. capsule: provides protection. plasmids. circular DNA in nucleoid. smaller ribosomes.
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What microscope is used in order to see prokaryotes?
an electron microscope.
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are microscopic channels in cell walls of plant cells enabling transport and communication between adjacent cells.

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Card 4

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What is the cell wall and what is its function?

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Card 5

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