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BIO150 > Chapter 6 - A tour of the Cell > Flashcards

Chapter 6 - A tour of the Cell Flashcards

1
Q

How do light microscopes work

A

use visible light and glass lenses to magnify and project images
- The lenses refract the light in a way that the image is magnified
- Allows us to study living cells
- Been revitalized recently by the addition of fluorescent markers and super resolution microscopy

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2
Q

Parameters in Microscopy

A
  • Magnification: the ratio of an objects image size to its actual size
    • Resolution: the clarity of the image; the minimum distance two points can be separated by and still be distinguished as separate points
      ○ Have a resolution of about 0.2 um
    • Contrast: the difference in brightness between the light and dark areas of an image
      ○ Enhanced through staining
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3
Q

Electron Microscope

A

focuses a beam of electrons through the specimen or onto its surface for higher resolution imaging
- In order to prepare the specimen, it often leads to cells being killedT

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4
Q

Types of EM

A
  • Scanning Electron Microscopes: Scans the surface of the sample which excites electrons, which these secondary electrons are then detected by a device which translates the electrons into an image of the specimen’s surface which appears to be 3d
    ○ especially useful for the detailed study of the topography of a specimen
  • Transmission Electron Microscope: aims an electron beam through a thin section of the specimen, which has been stained with atoms of heavy molecules and have attached to cellular structures, creating an image of the internal structure of cells
    ○ A new type was developed called Cryo-electron Microscopy which allows specimens to be preserved at extremely low temperatures, which allows visualization of structures in their cellular environments
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5
Q

Cell Fractionalization

A

a technique for determining cell structure and function by taking cells apart and separating major organelles and other subcellular structures

  • Requires a centrifuge which spins the disrupted cells, while differential centrifuge separates components based on their size
    ○ At faster speeds, the smaller the components form the supernatant, at slower speeds, the pellets consist of larger components
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6
Q

Parts of an Animal Cell

A
  • Nucleus:
    ○ Nuclear envelope:
    ○ Nucleolus:
    ○ Chromatin:
    • Endoplasmic Reticulum:
    • Cytoskeleton:
    • Mitochondria:
    • Lysosomes:
    • Golgi Apparatus:
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7
Q

Parts in a Plant Cell

A
  • Nucleus
    ○ Nuclear Envelope
    ○ Nucleolus
    ○ Chromatin
    • Rough ER and Smooth ER
    • Golgi Apparatus
    • Mitochondrion
    • Plasma Membrane
    • Cell Wall:
    • Plasmodesmata:
    • Chloroplasts:
    • Cytoskeleton
      Central Vacuole
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8
Q

Nucleus

A

contains the genetic material in the form of chromosomes in eukaryotic cells
- Directs protein synthesis and is enclosed by the nuclear envelop which is a lipid bilayer with perforated pores

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9
Q

Nuclear Lamina

A

lines the nuclear envelope besides at the pores and is a network array of protein filaments which maintain the shape by mechanically supporting the envelope
- Assisted by the nuclear matrix which extend throughout the nuclear interior
- Both help organize genetic material so it functions effectively

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10
Q

Nucleolus

A

a structure in the nucleus consisting of chromosomal regions containing and synthesizing rRNA molecules as well as assembling Ribosomes
- Can be two or more depending on species and stage of cells reproductive life cycle

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11
Q

Ribosomes

A

complexes made of rRNA and proteins which carry out protein synthesis
- Not considered organelles and lack a membrane

  • can either be free floating in the cytosol and create proteins that function in the cytosol
    • Can also be bound ribosomes which create proteins destined for membrane insertion, organelle packaging and secretion
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12
Q

Endomembrane system:

A

carries out protein synthesis, protein transport in and around the membrane and organelles, the metabolism and movement of lipids as well as detoxification of poisons
- Membranes are connected either physically or through vesicular transfer

Includes:
- nuclear envelope,
- endoplasmic reticulum,
- golgi apparatus,
- lysozomes,
- various type of vesicles and vacuoles
- plasma mebrane

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13
Q

Endoplasmic Reticulum

A

an extensive network of membranes that are called cisternae
- its a membrane which separates the internal compartment known as the lumen/cisternal space from the cytosol

  • both smooth and rough ER
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14
Q

Function of Smooth ER

A
  • Important in synthesizing lipids, including oils, steroids and new membrane phospholipids
  • help detoxify drugs and poisons by usually adding hydroxyl groups to drug molecules making them more water soluble and able to be flushed out
  • stores calcium ions in the ER lumen of muscle cells
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15
Q

Functions of RER

A
  • Synthesizes and secretes proteins such as glycoproteins; proteins with carbohydrates covalently bonded to them
  • Is a membrane factory for the cell and grows by adding membrane proteins and phospholipids to its own membrane
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16
Q

Golgi Apparatus

A

consists of stacks of flat membranous sacs that modify, store and route products of the ER(proteins)
- Extensive in cells specialized for secretion
- Has distinct cis and tran faces for the membranous stacks which are respectively the receiving and secreting sides
○ Cis means same side, referring to the same side as ER

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17
Q

Functions of the GOlgi

A
  • Products which pass through the golgi are modified in the transit from cis to tran sides
    • Golgi also manufactures molecules like polysaccharides
    • Involved in sorting and exporting of molecules by tagging them to direct where they go in or out of the cell through vesicles
18
Q

Cisternal Maturation Model

A

states the cisternae progress forward from cis to trans regions, carrying and modifying molecules as they move
- Reality may be that there is movement in the outer regions while the inner remains still

19
Q

Lysosomes

A

membranous sac of hydrolytic enzymes which many eukaryotic cells use to hydrolyze macromolecules
- Excessive leakage from large number of lysosomes can destroy a cell by self-digestion, 1 breaking down will not
- Created by the rough ER and transferred to the Golgi for processing

20
Q

Process of Lysosome Digestion

A
  • Phagocytosis:
    ○ engulf smaller organisms which allows the food vacuole to be fused to a lysosome
    ○ Enzymes digest the food and products such as sugars, amino acids pass into the cytosol
    • Autophagy: cell renewal/recycling
      ○ a damaged organelle, becomes surrounded by a double membrane which a lysosome then fuses with
      ○ Lysosome enzymes dismantle the inner membrane and enclosed material resulting in small organic compounds being released into the cytosol for reuse
21
Q

Lysosome Storage Disease

A

when hydrolytic enzymes are lacking leading to the accumulation of indigestible material and interferences with cellular activities

22
Q

Vacuoles

A

large vesicles derived from the endoplasmic reticulum and golgi apparatus which has specialized functions in different cells
- Have elective membranes which transport solutes

Types:
- food vacuoles
- contractile vacuoles
- hydrolytic vacuoles
- central vacuoles

23
Q

Mitochondrion

A

the sites of cellular respiration which uses oxygen to drive the production of ATP by extracting energy from bonds between sugars, fats and other fuels

  • Found in nearly all eukaryotic cells including plant and fungi cells
  • The number of mitochondria’s in a cell directly correlates with the cell levels metabolic activity
    Can move around, change shape and fuse and divide into fragments; it’s a dynamic organelle
24
Q

Structure of Mitochondrion

A
  • Each of the two membranes enclosing are phospholipid bilayers with unique collections of embedded proteins

inner foldings called cristae which due to their folding, give the inner membrane a large surface area, enhancing its productivity of cellular respiration

  • Intermembrane space is the narrow region between the inner and outer membrane
  • Mitochondrial matrix is enclosed by the inner membrane which contains many different enzymes as well as mitochondrial DNA and ribosomes
25
Q

Chloroplasts

A
  • Chloroplast: found in plants and algae, are the site of photosynthesis which converts solar energy to chemical energy by absorbing sunlight and using it to synthesis sugars from Co2 and water.
  • Contain chlorophyl, and other enzymes and molecules associated with the photosynthetic production of sugar
  • dynamic in behavior like mitochondria
26
Q

Structure of Chloroplasts

A
  • The contents are partitioned from the cytosol by an envelope consisting of two membranes, separated by a narrow intermembrane space
  • Inside the membranous system are thylakoids in the form of flattened, interconnected sacs which can be stacked into granums and contain chlorophyl pigments
  • The fluid outside the thylakoids is the stroma which contains Chloroplast DNA as well as ribosomes and enzymes
27
Q

Peroxisomes

A

a single membrane which contain enzymes that remove hydrogen atoms from various substrates and transfer oxygen
- Creates hydrogen peroxide(H2O2) which in itself is toxic, but the organelle contains an enzyme which converts it to water

  • detoxifies in the liver
  • uses oxygen to break down fatty acids as fuel for cellular respiration
28
Q

Cytoskeleton

A

a network of fibers extending throughout the cytoplasm and serve a variety of mechanical, transport and signaling functions

  • Prokaryotes also have similar cytoskeletons made up of proteins
  • Made up of 3 fibres; microtubes, microfilaments, intermediate filaments
29
Q

Functions of Cell Cytoskeleton: Support

A
  • The most obvious function of the cytoskeleton is to give mechanical support to the cell and to maintain its shape
    • Especially important for animal cells which lack cell walls
  • Provides anchorage for other organelles and cystolic enzymes.
  • Extremely dynamic and can be quickly dismantled and set up in a new location, changing the shape of the shell
30
Q

Functions of Cytoskeleton: Cell Motility

A

the interaction with Motor Proteins to induce changes in cell location and the movement of cell parts

  • Outside the cell, cytoskeletal elements and motor proteins work to move whole cells
  • Inside the cell, vesicles use motor proteins ‘feet to walk’ along a track provided by the cytoskeleton.
31
Q

Components of the cytoskeleton

A

Microtubules:a hollow rod composed of tubulin proteins which make up part of the cytoskeleton in all eukaryotic cells
- grow in length by adding tubulin dimers and can be disassembled when needed

Microfilaments: a twisted double chain of actin proteins which make up the cytoskeleton and work with myosin to cause cell contractions
- Can occur as linear or form structural networks when it binds with certain proteins
- Structural role is to bear tension

Intermediate Filaments: found in the cell of animals and made of keratin proteins coiled together which are specialized for bearing tension and are more permanent
- Intermediate in size between Microtubules and microfilaments

32
Q

Function of Microtubules

A
  • Support and shape the cell and serve as tracks with motor proteins can move along
  • Guide vesicles from the ER to the Golgi and from the Golgi to the Plasma membrane
  • Involved in the separation of chromosomes during cell division
33
Q

Function of Microfilaments

A

-help support the cells cortex; shape

-They are known for their role in cell motility:

  • actin and myosin filaments interact to cause contractions of muscular cells
  • In some white blood cells and protists, actin and myosin are also involved in movement of cells which crawl along surfaces through pseudopodia
  • In plant cells, actin-protein interactions contribute to cytoplasmic streaming
34
Q

Function of Intermediate Filaments

A
  • Sturdy and play a role in reinforcing the cell shape
  • fixesand achors the position of organelles and nucleus
35
Q

Cilia

A

Cilia: a short appendage containing microtubules
- Usually occur in large numbers on cell surface

36
Q

Types of Cilia

A
  • Motile cilia are specialized for locomotion or moving fluid past the cell
    • Formed from a core of 9 outer doublet microtubules and two inner single microtubules unsheathed in an extension of the plasma membrane(9+2 arrangement)
  • Primary cilium are non-motile and are arranged in a 9+0 arrangement acting as a single receiving antenna
37
Q

Dyneins

A

found in cilia and flagella it’s a large motor protein extending between microtubule doublets with ATP hydrolysis driving the changes in dynein shape leading to the bending of cilia and flagella
- Typically has ‘two feet’ with one attached while the other reattaches one step further

38
Q

Cell Wall

A

a protective layer external to that of the plasma membrane which protects the cell, maintains its shape and prevents excessive uptake of water

39
Q

process of developing a cell wall

A
  • Originally a young plant cell secretes a primary cell wall; a relatively thin and flexible wall which is glued to adjacent primary cell walls by the middle lamella
  • When the cell stops growing some strengthen its wall by secreting hardening substances while others create a secondary cell wall; often deposited in several laminated layers with a strong and durable matrix that affords cell protection and support
40
Q

Extracellular Matrix

A

the meshwork surrounding animal cells consisting of glycoproteins, polysaccharides and proteoglycans
- Super important in regulating cell life by communicating through integrins
- Can influence the activity of genes in the nucleus through chemical and mechanical signals
- Can coordinate the behavior of all cell tissue through triggering signaling pathways and changing the set of proteins

41
Q

Cell Junctions in Plants

A
  • Plasmodesmata: an open channel through the cell wall which connect the cytoplasm of adjacent cells allowing the transfer of water, small solutes and larger molecules to pass through
  • Appear to move through with the help of the cytoskeleton
42
Q

Types of Junctions in Animal Cells

A
  • Tight Junctions: prevents the leakage of material through the space between cells
  • Desmosomes: functions as rivet, fastening cells together
  • Gap Junctions: consisting of proteins surrounding a pore allowing the passage of materials between cells which are similar to plasmodesmata however they are not lined with a membrane

BIO150 (19 decks)

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