Th1L01 Cells and organelles


Cells and organelles
Emma Allde
Flashcards by Emma Allde, updated more than 1 year ago
Emma Allde
Created by Emma Allde over 7 years ago

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Question Answer
Nothing less than _______ can be called living. A cell
An organised assembly of cells and their extracellular products which carry out similar and coordinated activities within the body Tissue
An assembly of tissues coordinated to perform specific functions within the body Organ
An assembly of organs with specific, related activities, sharing regulatory influences System
A diffuse functional network of cells situated in many parts of the body, sharing specific activities System
The three main characteristics of a prokaryote (3) 1. single-celled 2. circular, free-lying chromosome 3. no membrane-bound organelles
Eukaryotic DNA is linear and serial
Main components of a virus nucleic acid (DNA or RNA) and proteins
Viruses subvert _________ machinery to make more viruses protein synthesis
Viruses are not cells or organisms in the strict sense because.... (2) 1. They lack a plasma membrane 2. Only operate chemically within host cells
Extra-chromosomal DNA is found in plasmids (pro and eu) and mitochondria (eu only)
Ribosome of prokaryotes 70S
Ribosome of eukaryotes 80s (70s in mitochondria)
Transmission Electron Microscope (TEM) to look inside a cell (electrons go through the specimen)
Scanning Electron Microscope (SEM) to see the cell surface(electrons scattered off cell surface by heavy metal coating e.g. Au)
Both types of EM involve elaborate preparation and can only evaluate ___ cells dead
Life span of enterocytes 5-6 days
Life span of erythrocytes 115 days
Life span of neurons lifespan
Limits of the maximum size of a cell diffusion distance
Diffusion efficiency at a distance above _____ is reduced 50μm
Surface Area (SA) : Volume (V)
Sphere: SA = 4Πr^2
Sphere V= 4/3Πr^3
How to specialised cells overcome this problem of diffusion distance? (3) Thin processes, "giant" multinucleated cells and gap junctions
Thin processes Direct transport of substances around cell via cytoskeleton e.g. neurones and oligodendrocytes
Giant” multinucleate cells Gene expression can occur in more than one place e.g. skeletal muscle cells
Types of protein filament that make up cytoskeleton actin, IF and MT
Cytosol 1. The aqueous environment within the plasma membrane 2. Together with organelles make up the cytoplasm
The only organelle visible by light microscopy nucleus, as it is the largest organelle in the cell (diam. 3-10μm)
Chromatin complex of DNA/histone and non-histone proteins
DNA winds around histones into _______ nucleosomes
Length of naked DNA 1.8m
Length of DNA packaged into nucleosomes 95 mm
DNA length post mitosis 120μm
Non-dividing chromatin is ____ decondensed
Nucleolus (3) 1. Where rDNA is transcribed and ribosome subunits assembled 2. Contains a nuclear envelope surrounded by two layers of membrane 3. Nuclear pores allows transport in and out
Smooth endoplasmic reticulum (SER) (2) 1. Biosynthesis of lipids, steroids 2. Metabolise carbohydrates/steroids
Rough endoplasmic reticulum (RER) (3) Coated with ribosomes 1. Ribosomes are involved in the translation, proteins for secretion or insertion into cell membrane 2. Proteins are folded 3. Vesicles are budded from RER and transported to the Golgi body for further transport and modification
Golgi body composition 4-8 closely-stacked, membrane-bound channels (many stacks/mammalian cell)
Golgi 1. Modifies proteins delivered from RER e.g. by adding sugar (carbohydrate) or lipid (fat) side-chains 2. Synthesise/package materials to be secreted 3. Direct new proteins to their correct compartments 4. Transport lipids around cell 5. Create lysosomes 6. Vesicles bud off bud off from the Golgi
Golgi vesicles fuse with the inner surface of the plasma membrane and release their contents (exocytosis) e.g. hormones and neurotransmitters
SER concentrations are high in the liver and kidneys as well as endocrine glands that produce hormones
RER concentrations are high in nuclear membrane; many found in pancreatic secretory cells because they require a lot of enzymes
Mitochondria composition (3) 1. Two layers of membrane, 0.5-2μm long 2. Contain mDNA that encode some of their proteins 3. Inner membrane in folds - cristae – increase surface area
Mitochondria 1. Sugars oxidised to generate ATP (Krebs cycle enzymes located in different parts of the membrane)
Number of _______ per cell reflects metabolic activity mitochondria
Functional vesicles lysosomes, peroxisomes
Lysosomes composition (2) 1. Electron-dense spheres with diameter 80-800nm 2. Lysosomal proteins are tagged with mannose -6- phosphate
Lysosomes 1. Involved in protein, RNA and DNA degradation/recycle/excrete 2. Contain powerful enzymes that require low pH
Peroxisomes composition Large (0.5-1.5μm), not very electron-dense
Peroxisomes 1. Involved in detoxification and phospholipid synthesis 2. Enzymes which generate (and degrade) H2O2
Zellweger syndrome Inherited absence of peroxisomes
Myoclonic Epilepsy with Ragged Red Fibers (MERRF syndrome) (2) 1. Mutation of mitochondrial gene for tRNA-lys 2. Disrupts synthesis of oxidative phosphorylation enzymes
Hutchinson-Gilford Progeria (3) 1. Mutation in lamin A part of the nuclear envelope 2. Distorted shape of nucleus (blebbed) 3. Production of unique progerin protein
Tay Sachs Disease 1. Mutation of the lysosomal hexosaminidase-A enzyme 2. Causes accumulation of ganglioside that is neurotoxic
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