Ultrastructure of Cells

Ultrastructure of Cells Prokaryotic Cells Define prokaryote A prokaryote is a simple cell that lacks a nucleus and all membrane-bound organelles ………………………………………………………………………………………………………………………………………………….......... Bacteria are prokaryotic cells ………………………………………………………………………………………………………………………………………………….......... Label the following diagram of a prokaryotic cell 1 2 6 3 7 5 4 Plasmid 1. ………………………………………………………………… Cell wall 5. ………………………………………………………………… Glycocalyx (slime capsule) 2. ………………………………………………………………… Ribosome (70S) 6. ………………………………………………………………… Cell membrane (with pili) 3. ………………………………………………………………… Flagellum 7. ………………………………………………………………… Nucleoid 4. ………………………………………………………………… Distinguish between the genophore and plasmids The genophore is a circular DNA molecule that contains the genetic material (i.e. bacterial ‘chromosome’) ………………………………………………………………………………………………………………………………………………….......... Plasmids are additional autonomous DNA molecules that can be transferred via bacterial conjugation ………………………………………………………………………………………………………………………………………………….......... State the composition of a bacterial cell wall The bacterial cell wall is composed of peptidoglycan ………………………………………………………………………………………………………………………………………………….......... Outline the role of pili Attachment pili allow bacteria to adhere to surfaces ………………………………………………………………………………………………………………………………………………….......... Sex pili allow bacteria to exchange genetic information (plasmids) via bacterial conjugation ………………………………………………………………………………………………………………………………………………….......... Describe how bacterial cells divide • Bacterial cells divide by binary fission (asexual reproduction) ………………………………………………………………………………………………………………………………………………….......... • The circular DNA molecule is copied and then is anchored to the plasma membrane ………………………………………………………………………………………………………………………………………………….......... • The DNA loops are drawn apart as the cell elongates, before dividing (cytokinesis) to form two clones ………………………………………………………………………………………………………………………………………………….......... Eukaryotic Cells Label the following diagram of an animal cell 2 1 3 10 4 9 5 8 6 7 Nucleus 1. ………………………………………………………………… Lysosome (or peroxisome) 6. ………………………………………………………………… Nucleolus 2. ………………………………………………………………… Golgi apparatus 7. ………………………………………………………………… Rough Endoplasmic Reticulum (rER) 3. ………………………………………………………………… Plasma membrane 8. ………………………………………………………………… Smooth Endoplasmic Reticulum (sER) 4. ………………………………………………………………… Ribosome (80S) 9. ………………………………………………………………… Mitochondrion 5. ………………………………………………………………… Cytosol / Cytoskeleton (NOT cytoplasm) 10. ………………………………………………………………… Explain how the compartmentalisation of eukaryotic cells allows for greater complexity Eukaryotic cells contain sub-cellular structures called organelles (i.e. ‘little organs’) ………………………………………………………………………………………………………………………………………………….......... These membrane-bound compartments perform specialised functions that provide eukaryotic cells with a ………………………………………………………………………………………………………………………………………………….......... greater level of functional complexity ………………………………………………………………………………………………………………………………………………….......... State the role of the following organelles Nucleus The nucleus is a double membrane structure (with pores) that stores DNA It is the site of transcription (RNA synthesis) Nucleolus The nucleolus is a region within the nucleus where ribosomes are assembled Endoplasmic The endoplasmic reticulum is a membrane network that transports materials Reticulum Golgi Apparatus between organelles (via vesicles) The golgi apparatus is involved in the sorting, storing, modification and export of secretory products from the cell Ribosomes Ribosomes are responsible for protein synthesis (translation) They can be found freely within the cytosol or may be embedded on the rough ER Mitochondria Lysosome Mitochondria are responsible for aerobic respiration (ATP synthesis via oxygen) The lysosome is responsible for the breakdown of macromolecules (the digestion of toxic metabolites occurs within the peroxisome) Distinguish between the structure and function of smooth ER and rough ER Rough ER is embedded with ribosomes and is therefore responsible for the transport of proteins ………………………………………………………………………………………………………………………………………………….......... Smooth ER is NOT embedded with ribosomes and is involved in the transport and synthesis of ………………………………………………………………………………………………………………………………………………….......... carbohydrates and lipids ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Label the following micrograph of a plant cell Nucleus 1. ………………………………………………… 6 Nucleolus 2. ………………………………………………… 1 Chloroplast 3. ………………………………………………… 2 Large, central vacuole 4. ………………………………………………… Cell wall 4 5. ………………………………………………… 3 Mitochondrion 6. ………………………………………………… 5 Outline five differences between animal and plant cells Plant cells may have chloroplasts, animal cells do not 1. …………………………………………………………………………………………………………………………………………………... …………………………………………………………………………………………………………………………………………………... Plant cells have a cell wall (and connecting plasmodesmata), animal cells do not 2. …………………………………………………………………………………………………………………………………………………... …………………………………………………………………………………………………………………………………………………... Plant cells have a large, central vacuole whereas animal cells have small, temporary vacuoles (if any) 3. …………………………………………………………………………………………………………………………………………………... …………………………………………………………………………………………………………………………………………………... Animal cells have cholesterol in their plasma membranes, plant cells do not 4. …………………………………………………………………………………………………………………………………………………... …………………………………………………………………………………………………………………………………………………... Plant cells store excess glucose as starch, animal cells store excess glucose as glycogen 5. …………………………………………………………………………………………………………………………………………………... …………………………………………………………………………………………………………………………………………………... State the composition of a plant cell wall The cell wall of a plant cell is composed of cellulose ………………………………………………………………………………………………………………………………………………….......... Identify the function of chloroplast and identify where it is found in the plant tissue Chloroplast are the organelle responsible for photosynthesis (they contain the pigment chlorophyll) ………………………………………………………………………………………………………………………………………………….......... Chloroplast are found in photosynthetic tissues (i.e. in the palisade mesophyll of the leaf) ………………………………………………………………………………………………………………………………………………….......... Chloroplast are NOT found in all plant tissues (i.e. they are absent from root cells) ………………………………………………………………………………………………………………………………………………….......... Prokaryotic vs Eukaryotic Cells Compare prokaryotic and eukaryotic cells according to the following features Prokaryote DNA DNA is naked DNA is bound to histone proteins DNA molecules are circular DNA molecules are linear DNA is freely floating in the cytosol (specifically in the nucleoid region) Does NOT have any membrane-bound Organelles organelles Ribosomes are 70S in size Reproduce via binary fission Reproduction Reproduction is asexual (cells haploid) Average Size Eukaryote Smaller (typically 1 – 5 µm) DNA is contained within the nucleus Has membrane-bound organelles Ribosomes are 80S in size May reproduce via numerous methods (mitosis, meiosis, budding, etc.) Reproduction may be sexual or asexual (cells may be diploid) Larger (typically 10 – 100 µm)