Organization of Cells Flashcards
1
Q
Eukaryotic Cells
A
- DNA found in nucleus
- Plasma Membrane: a selectively permeable, lipid bilayer surrounding each cell
- Cytoplasm: the interior of a cell (minus the nucleus) containing organelles suspended in a jelly-like substances called the cytosol
2
Q
Animal Vs Plant Cells - Organelles
A
Animal:
- no cell wall
- one or more small vacuole
- centrioles present
- chloroplast absent
- plastids absent
- lysosomes present
- cilia present
Plants:
- cell wall present (formed of cellulose)
- one large central vacuole
- centrioles only present in lower plant forms
- chloroplasts present
- plastids present
- lysosomes usually not evident
- cilia absent in most
3
Q
Endomembrane System
A
- consists of the nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles & plasma membrane
- connected via direct physical continuity or the transfer of vesicles
4
Q
Nucleus & Its 2 Structures
A
- contains genetic material as molecules called chromosomes, made up of chromatin, which contain DNA complexed with proteins
- Nuclear Envelope: a double membrane, each being a lipid bilayer
- Nucleolus: location of rRNA transcription and ribosome assembly
5
Q
Ribosomes Definition & 2 Types
A
- complexes of protein & rRNA responsible for protein synthesis
- Free Ribosomes: suspended in the cytosol
- Bound Ribosomes: associated to endoplasmic reticulum or nuclear envelope
6
Q
Endoplasmic Reticulum (ER) - Definition and Its 3 Types
A
- membranous system of interconnected tubules & flattened sacs (cisternae)
- ER Lumen: the internal compartment
- Smooth: involved in numerous metabolic processes including lipid synthesis, drug detoxification and calcium storage
- Rough: covered in ribosomes synthesizing proteins to be exported. Involved in protein glycosylation & membrane synthesis
- Transitional: region of rough ER that transports vesicles to other regions of the cell
7
Q
Golgi Apparatus
A
- series of 4-8 flattened membranous sacs called cisternae
- contains directionality; cis face is oriented towards the ER and receives vesicles, trans face sorts molecules and releases vesicles for transport
- alters structure of macromolecules received from the ER
8
Q
Lysosomes
A
- a membranous sac with an acidic interior, containing hydrolytic enzymes for the hydrolysis of macromolecules
- Phagocytosis: the endocytosis or large particles/microorganisms coupled to digestion
- Autophagy: recycling of a cell’s organic material
9
Q
Vacuoles - Definition & 5 Types
A
- large vesicles with an internal solution differing in composition from the cytoplasm
- Food: formed by phagocytosis
- Contractile: pump excess water out of the cell; found in aquatic unicellular eukaryotes
- Hydrolytic: similar to lysosomes, found in plants & fungi
- Small: storage of organic compounds like toxins
- Central: found in plant cells, stores inorganic ions & contributes to cell growth and structure
10
Q
Mitochondria
A
- sites of cellular respiration, producing ATP from fuels and oxygen
- found in nearly all eukaryotic organisms
- enclosed by double membrane, each being a lipid bilayer
- contains its own DNA and ribosomes
- inner membrane is convoluted & separates the mitochondrial matrix from the inter-membrane space
- enzymes of cellular respiration found in both the mitochondrial matrix and the inner membrane
11
Q
Chloroplasts - Features & Structures
A
- specialized plastic that are sites of photosynthesis, producing sugars from CO2, H2O and light
- enclosed by double membrane, each being lipid bilayer, and contains its own DNA and ribosomes
- Thylakoids: membranous system of flattened, interconnected sacs
- Granum: stack of thylakoids
- Stroma: fluid outside of the thylakoids
- *enzymes of photosynthesis split between the stroma and the thylakoids
12
Q
Endosymbiont Theory
A
- states that mitochondria & chloroplasts evolved from bacteria
- explains many unusual properties of mit. and chloro. such as the presence of its own peroxisomes and DNA, & the doubled membrane
13
Q
Peroxisomes
A
- bound by a single lipid bilayer membrane
- contains enzymes to remove hydrogen atoms form molecules, transferring them to O2, producing H2O2 (hydrogen peroxide), which is then converted to H20
- involved in breakdown of fatty acids & detoxification of harmful compounds
14
Q
Cytoskeleton
A
- network of fibres extending throughout cytoplasm
- provides mechanical support & structure & anchorages for organelles
- involved in cell movement
- consists of microtubules, microfilaments and intermediate filaments
15
Q
Microtubules
A
- hollow rods made of dimers of alpha-tubulin & beta-tubulin with directionality
- contributes to cell shape & support
- serves as tracks for motor proteins
- Centrosome: region near nucleus, from which microtubules grow
- Centriole: pair of 9 sets of triplet microtubules in a centrosome
- Flagella & Cilia: microtubule-containing extensions of cell involved in motility, movement of fluid, and signalling
