2.3 – Eukaryotic Cells Eukaryotic cells will often join with other cells to form multicellular organisms.
2.3.1 - Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell
2.3.2 - Annotate the diagram from 2.3.1 with the functions of each named structure Nucleus - Contains the DNA of the cell, with pores in the nuclear membrane to allow movement of mRNA. Nucleolus - The location of synthesis of ribosomes for use in the cell. Rough endoplasmic reticulum - Ribosomes sit on the surface, synthesising proteins for use outside the cell. Smooth endoplasmic reticulum - Synthesises lipids and steroid hormones, as well as breaking down lipid-soluble toxins Golgi apparatus - Modifies, processes and packages macromolecules (especially proteins) into vesicles for transport within the cell Mitochondrion - The location of the reactions of aerobic respiration, providing energy for the cell in the form of ATP.
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Ribosomes - The free-floating ribosomes synthesise proteins that are used within the cell Cell membrane - A lipid bilayer that acts as a protective barrier for the cell. It contains chemical receptors and pores for the movement of ions and other molecules. Cytoplasm - Where the chemical reactions of life, including respiration, occur. This is mostly made up of water, but also some proteins (i.e. enzymes for metabolic reactions). Lysosomes - Membrane-bound vesicles that contain enzymes for intracellular digestion. It is important for cell defence, digesting harmful organisms and chemicals. Vacuoles - Store water to increase cell turgor.
2.3.3 - Identify structures from 2.3.1 in electron micrographs of a liver cell
2.3.4 - Compare prokaryotic and eukaryotic cells Both have:
Cell membrane
DNA
Ribosomes
Metabolism
Require energy
Cytoplasm
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The differences between them are: Prokaryotes
Eukaryotes
Smaller sized cell
Larger sized cell
Cell wall
No cell wall, except in plants
Naked DNA
DNA associated with histone proteins
Contain plasmids
No plasmids
DNA in a single loop
DNA in separate chromosomes
DNA found free-floating in the
DNA enclosed in the membrane-
cytoplasm
bound nucleus
No mitochondria
Mitochondria present
Smaller, 70S ribosomes
Larger, 80S ribosomes
No membrane-bound organelles
Contains membrane-bound organelles
2.3.5 - State the three differences between plant and animal cells Plant Cells
Animal Cells
Cell wall, made up of cellulose, causing a
No cell wall
more rectangular shape Contain chloroplasts, with chlorophyll to
No chloroplasts
absorb light for photosynthesis, causing the cell to appear green Contain a large vacuole, approximately 90%
Contain significantly
of cell volume, which stores water and ions.
smaller vacuoles.
Increases cell turgor.
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2.3.6 - Outline two roles of extracellular components Cell Wall - This is found around all plant cells, and is composed of cellulose. It maintains the shapes of the cell and provides structural support. It also prevents the excessive uptake of water. Animal Extracellular Matrix - this is a secretion, sometimes of glycoproteins. It sits between cells, and can perform many additional functions such as support, adhesion, filtering, as well as a basis for the formation of tissue.
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