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Transcript
Post-test questions 1. What does the cell theory state? – All living things are made up of cells – The cell is also the functional unit of life – All living cells come from pre-existing cells 2. What are cells? – The cell is the basic unit of life; the smallest structure capable of performing all the functions necessary for life. Cells are specialized in structure and function according to its job… e.g. nerve cell transmits electrical response e.g. muscle cells are able to contract and shorten e.g. red blood cells do not contain a nucleus and therefore they cannot divide. Additionally, their small size allows them to fit into tiny vessels Post-test questions 3. What is the main difference between prokaryotic and eukaryotic cells? – Prokaryotes lack a nucleus as well as membrane enclosed structures (e.g. bacteria); – whereas eukaryotes have a nucleus and possess membrane enclosed structures 1. pro = before 2. karyotic = nucleus 3. These were the first cells. 4. They were primitive, small, had no defined nucleus (no nuclear membrane), and no membrane bound cell organelles. 5. They had ribosomes 1. eu = true 2. karyotic = nucleus 3. These are modern cells. 4. They have a nucleus and membranebound organelles. 5. They are much larger (up to 1000X larger). 4. What is an organelle? – Small structures within a cell that have a specific structure and function Structure Composed of a bi-layer of phospholipids with proteins embedded in it Function • holds cell together and gives shape • regulates the movement of substances in and out of the cell Nuclear membrane Nuclear pore Nucleolus Chromatin Nucleoplasm Structure: • Dark granule in center of cell • Surrounded by a double membrane called the nuclear envelope/membrane Functions: – Controls cell activities through protein synthesis – Contains genetic info – Directs cell division – Site of DNA replication and transcription Structure • small, dark spot in nucleus • Made up of RNA • No membrane Function • makes rRNA, which then make ribosomes Structure: • a double membrane made of phospholipids which has nuclear pores Function – Separates nuclear material from cytoplasm – Pores allow RNA and proteins in & out of nucleus 1. Densely coiled DNA wrapped around histone proteins. 2. Is condensed into chromosomes before cell replication. This is the cytoplasm of the nucleus Structure • double membrane of phospholipids • inner membrane is very folded =CRISTAE (increased surface area) • fluid in between = MATRIX • has its own DNA Mitochondria are used to convert the chemical energy in food to ATP Function: • “powerhouse” – makes energy (ATP) for the cell in a process called CELLULAR RESPIRATION C6H12O6 + 6O2 6CO2 + 6H2O + ATP Cristae (inner folds) provides more surface area for enzyme reactions to make ATP Structure • membrane channels running from the nuclear envelope throughout cytoplasm. It is a transport system. 2 Types: •Has attached ribosomes. •Usually connected with the nuclear membrane. •Ribosomes make proteins and then place them in the rER •The rER packages proteins in a vesicle and sends them to the Golgi Body. SMOOTH ER: •Has no attached ribosomes. •Makes lipids and steroids. •Also detoxifies harmful material or waste products •You’ll find a lot of sER in liver cells and glands that make hormones. Structure • small, dense granules made of rRNA & protein • No membrane • 2 subunits (large & small) Function • site of protein synthesis (translation) • Usually attached to rER so proteins can be easily exported • Can be free in cytoplasm -proteins not exported (aka Polyribosome) Structure • Free floating group of ribosomes Function • makes large proteins (faster) with a single mRNA molecule (or golgi apparatus or golgi complex) Structure • stacks of flattened sacs • surrounded by vesicles Function • Collects, sorts, packages and distributes materials • modifies proteins and lipids from ER DNA copies a gene as RNA RNA moves through pore and attaches to ribosome to make protein Protein put into RER, then sent to Golgi in a vesicle Golgi modifies protein, stores it until needed, and sends it to plasma membrane in a vesicle. Protein released at the Plasma Membrane via exocytosis Structure • Small, membranous (bilayer) bound sac usually made by Golgi body Function • Storage sac (temporary storage) ex. H2O, food, digestive enzymes, hormones. 2 types: Transport vesicle: moves substances from ER to Golgi Secretory vesicle: moves substances from Golgi to cell membrane Structure Function • large vesicle (but small in animals) and typically one large in plants • Membranous sacs • Long term storage of H2O with dissolved sugars and salts Plant cell Vacuole Structure • Double membraned vacuoles with hydrolytic (digestive) enzymes Function • Hydrolysis! • destroys harmful substances • can kill the cell if it breaks open - “suicide sacs” • many in white blood cells • • • Also, breaks down organelles that are not working anymore in tadpoles destroys their tails in human embryos destroys webbing between fingers http://highered.mcgraw-hill.com/olc/dl/120067/bio01.swf LYSOSOME ANIMATION series of protein fibres in the cytoplasm • Maintains cell shape • Monorail to transport organelles around the cell • Assemble and disassemble as needed Made up of: 1. Microfilaments 2. Microtubules 3. intermediate filaments • • • • aka actin filaments Long & thin protein fibres Anchored to the plasma membrane Organelles move around the cytoplasm on these • • • • Gives structure and support to cell membrane Actin interacts with motor molecules such as myosin. In the presence of ATP, myosin pulls actin along Example: muscle cells Structure • Largest fibre • Cylinder shaped & made of tubulin (protein) Function • Anchor for organelles and monorail for organelle movement • Used to make cilia, flagellum & centrioles Structure • Intermediate size between actin filaments and microtubules • made of keratin Function • Keeps the nucleus in place • Cell-cell junctions, such as those holding skin cells tightly together Structure Function • ‘Watery gel’ between • Support & suspend cell membrane and organelles nuclear envelope • Provide water • Contains water with • allows diffusion to dissolved salts, proteins occur in cells & other organic compounds Structure • Double membrane of phospholipids • inside stacks of discs called GRANUM • contain: – their own DNA – ribosomes – enzymes Function • photosynthesis (light energy converted into chemical energy) ATP + 6CO2 + 6H2O → C6H12O6 + 6O2 Granum= contains chlorophyll which traps solar energy Structure • Tough, rigid outermost wall • made up of cellulose (very strong) Function • maintains cell shape and skeletal support