Topic 1 review cells

1
Topic 1 review cells

• Discuss the theory that living organisms are
  composed of cells.
• The Cell Theory states that
• All organisms are composed of one or more cells.
• All cells arise from pre-existing cells.
• All vital functions of an organism occur within
  cells.
• Cells are the most basic unit of life.
• Cells contain the hereditary information
  necessary for regulating cell functions and for
  transmitting information to the next generation
  of cells.

2

• There are however, exceptions
• Skeletal muscle contain a membrane, like most
  normal cells- but inside contain hundreds of
  nuclei.
• Some fungal hyphae are not divided into cells but
  have a multinucleate cytoplasm.
• Extracellular material (material outside the cell
  membrane), such as teeth and bone, forms a
  significant part of the body.
• Some biologists consider unicellular organisms to
  be acellular.

3

• State that a virus is a non-cellular structure
  consisting of DNA or RNA surrounded by a protein
  coat.
• Viruses are not cells. They are simple particles
  consisting of DNA and RNA wrapped in a protein
  coat. Viruses are not considered alive because
  they have no metabolism.

4
Explain three advantages of using light
microscopes.

• Light microscopes
• Display colour instead of monochrome (black and
  white) images.
• Provide a large field of view.
• Facilitate preparation of sample material.
• Allow for the examination of living material and
  the observation of movement.
• Cheap in comparison to electron microscopes

5
Outline the advantages of using electron
microscopes

• Electron microscropes
• Provide images of higher resolution and
  magnification than light microscopes.
• Resolution refers to the ability to distinguish
  two objects as seperate entities.
• Magnification refers to the ability to increase
  the size of a viewed object.

6

• Scanning Electron Microscopes (SEM) provide
  images of the specimen's surface while
  Transmission Electron Microscopes (TEM) provide
  images of a sample's interior. The resolution of
  an SEM is approximately half that of a TEM.
• May provide a three dimensional view.

7

• Define organelle.
• An organelle is a discrete structure within a
  cell, and has a specific function. A
  mitochondrion would be an example of an
  organelle.

8

• membrane-enclosed organelle, found in most
  eukaryotic cells
• convert NADH and NADPH into energy in the form of
  ATP via the process of oxidative phosphorylation.
  
• Mitochondria contain DNA that is independent of
  the DNA located in the cell nucleus. According to
  the endosymbiotic theory, mitochondria are
  descended from free-living prokaryotes.

9
To draw a mitochondria
10
Golgi body

• The primary function of the Golgi apparatus is to
  process and package macromolecules synthesised by
  the cell, primarily proteins and lipids. The
  Golgi apparatus forms a part of the endomembrane
  system present in eukaryotic cells.

11
To draw a golgi
12
Endoplasmic Reticulum

• Protein translation, folding, and transport of
  proteins to be used in the cell membrane (e.g.,
  transmembrane receptors and other integral
  membrane proteins), or to be secreted
  (exocytosed) from the cell (e.g., digestive
  enzymes) sequestration of calcium and
  production and storage of glycogen, steroids, and
  other macromolecules.1

13
Remember may be rough or smooth ( rough
ribosomes)
14
Vacuoles

• membrane-bound compartments within some
  eukaryotic cells that can serve a variety of
  secretory, excretory, and storage functions.
• Plants have large central vacuole

15
(No Transcript)
16
Lysosomes

• contain digestive enzymes (acid hydrolases).
• digest excess or worn out organelles, food
  particles, and engulfed viruses or bacteria.
• membrane surrounding a lysosome prevents the
  digestive enzymes inside from destroying the
  cell.
• fuse with vacuoles and dispense their enzymes
  into the vacuoles, digesting their contents. They
  are built in the Golgi apparatus.

17
(No Transcript)
18

• is a small, dense organelle in cells that
  assembles proteins. Ribosomes are about 20nm in
  diameter
• translates messenger RNA (mRNA) to build a
  polypeptide chain (e.g., a protein) using amino
  acids delivered by Transfer RNA (tRNA).
• It can be thought of as a giant enzyme (in fact,
  it's not a protein, so that it can't be called an
  enzyme, but a "ribozyme") that builds a protein
  from a set of genetic instructions

19
(No Transcript)
20
Centrioles

• A centriole in biology is a barrel shaped
  microtubule structure found in most animal cells
  and algae though not often in plants. The walls
  of each centriole are usually composed of nine
  triplets of microtubules
• plays a role in organizing the mitotic spindle,
  which in turn helps the cells to divide

21
(No Transcript)
22
Chloroplast

• found in plant cells and eukaryotic algae that
  conduct photosynthesis.
• absorb sunlight and use it in conjunction with
  water and carbon dioxide to produce sugars.
• capture light energy from the sun to conserve
  free energy in the form of ATP and reduce NADP to
  NADPH through a complex set of processes called
  photosynthesis.
• Chloroplasts are members of a class of organelles
  known as plastids

23
(No Transcript)
24
Relative size p 3 sg

• Molecules (1 nm) (Smallest)
• Cell membrane thickness (10 nm)
• Viruses (100 nm)
• Bacteria (1 µm)
• Organelles (lt10 µm)
• Most cells (lt100 µm) (Largest)

25
Calculate magnification p 3 sg

• Drawings should show cells and cell
  ultrastructure.
• Include
• A scale bar ------ 1 µm
• Magnification 250
• To calculate magnification
• Magnification Measured Size of Diagram Actual
  Size of Object

26
surface area to volume ratio as a factor limiting
cell size. P3 sg

• A cell needs a large surface area in order to
  carry out metabolic functions (as chemical
  reactions require a surface).
• As a cell grows, it needs to carry out more and
  more reactions. Therefore, since a cell has to
  maintain a certain surface area to volume ratio,
  its size is limited.

27

• The rate of exchange of materials
  (nutrients/waste) and energy (heat) is a function
  of its surface area.
• Thus As a cell grows in size (volume), the
  distance increases between the cytoplasm at the
  center of the cell and the cell membrane. The
  rate of chemical exchange with the surrounding
  environment may hence become too low to maintain
  the cell. It is not able to excrete waste quickly
  enough or take in important minerals.
• Volume of a cell determines requirements while
  surface area determines supply

28
(No Transcript)
29
unicellular organisms carry out all the functions
of life

• Unicellular organisms contain all the necessary
  structures required to carry out life processes
  as independent organisms, such as gas exchange,
  digestion, asexual reproduction, and nutrient
  management. An Amoeba would be an example.

30
cells in multicellular organisms differentiate

• During the early development stages of
  multicellular organisms, cells undergo
  differentiation, becoming specialized in
  structure and function.
• are then organized into tissues and organs.
• Cells of multicellular eukaryotes express only a
  small fraction of their genes, allowing them to
  perform highly specialized functions.

31
Define tissue, organ and organ system sg p 1

• Tissue An integrated group of cells that share
  stucture and are adapted to perform a similar
  function.
• Organ A combination of two or more tissues which
  function as an integrated unit, performing one or
  more specific functions.
• Organ system A group of organs that specialize
  in a certain function together.

32
Prokaryotic Cells page 5 sg

• Draw a generalized prokaryotic cell as seen in
  electron microscopes.
• The diagram should include the cell wall, plasma
  membrane, mesosome, cytoplasm, ribosomes, and
  nucleoid ( region containing naked DNA).
• See next slide

33
(No Transcript)
34
What do they do page 5 sg

• Cell Wall Maintains the cell's shape and give
  protection.
• Plasma Membrane Regulates the flow of materials
  (nutrients, waste, oxygen, etc.) into and out of
  the cell.
• Mesosome Increases the cell's surface area to
  volume ratio. Now widely regarded as an artifact
  of the process that prepares specimens for
  electron microscopy.
• Cytoplasm Holds and suspends the cell's
  specialized organelles and enzymes.
• Ribosome Protein synthesis.
• Naked DNA Contains the cell's genetic material.

35

• State that prokaryotes show a wide range of
  metabolic activity including fermentation,
  photosynthesis and nitrogen fixation.
• Prokaryotes demonstrate a range of metabolic
  activity
• Cyanobacteria (often referred to as blue-green
  algae although they are not algae) obtain their
  energy through photosynthesis.
• Bacteria can convert organic substances into
  other organic substances. (i.e., glucose to
  lactic acid during anaerobic respiration)
• Some bacteria can fix nitrogen from the air,
  converting it into ammonia (which is biologically
  available).

36
Eukaryotic Cells page 6 sg

• Draw a diagram to show the ultrastructure of a
  generalized animal cell as seen in electron
  micrographs.
• Diagram of an animal cell
• Should include ribsomes, the RER, lysosome, Golgi
  apparatus, mitochondrian, and nucleus. Not- just
  the ultrastructure meaning a small part.

37
Eukaryote
38
function of each of these organelles

• Ribosomes Main site of protein synthesis
• Rough endoplasmic reticulum (rER) Packages the
  proteins synthesized in the ribosomes.
• Lysosome Digests macromolecules and contain
  digestive enzymes.
• Golgi apparatus Modifies, stores and routes
  products of the endoplasmic reticulum.
• Mitochondrion Serves as the site of cellular
  respiration.
• Nucleus Contains a cell's genetic material

39
Compare prokaryotic and eukaryotic cells.

• Prokaryotic cells vs. Eukaryotic cells
• Contain naked DNA vs. DNA associated with protein
  
• DNA in cytoplasm vs. DNA enclosed in a nuclear
  envelope
• No membrane-enclosed organelles vs.
  membrane-enclosed organelles (e.g., mitochondria,
  chloroplasts)
• 70S vs. 80S ribosomes

40
three differences between plant and animal cells.

• Only plant cells have
• Cell walls
• Chloroplasts
• Large central vacuoles and tonoplast
• Plasmodestmata
• Starch granules for storage of carbohydrates

• Only animal cells have
• Centrioles
• Cholesterol in the plasma membrane
• Glycogen for storage of carbohydrate

41
composition and function of the plant cell wall.

• The main component of plant cell walls is
  cellulose. Cellulose molecules are arranged in
  bundles called microfibrils. These give the cell
  wall great tensile strength and allow high
  pressures to develop inside the cell.

42
(No Transcript)
43
Membranes page 7 sg

• Draw a diagram of the fluid mosaic model.
• Diagram should shown the phosopholipid bilayer,
  cholesterol, glycoproteins, and integral and
  peripheral proteins. Use the term plasma membrane
  not cell surface membrane for the membrane
  surrounding the cytoplasm.

44
(No Transcript)
45
hydrophobic and hydrophilic properties
46
the functions of membrane proteins

• including hormone binding sites
• enzymes
• electron carriers
• channels for passive transport
• pumps for active transport.

47

• Channel proteins allow a particular molecule to
  cross membrane freely
• BIOL 230 Lecture Guide - Transport of Substances
  Across a Membrane by Channel Proteins

48

• Receptor proteins are shaped so a specific
  molecule (e.g., hormone or other molecule) can
  bind to it.

49

• Electron carriers. Remember the electron
  transport chain found in mitochondria and
  chloroplast. We will go over these later

50
Passive transport channels p 9 sg

• Shockwave (go to passive transport-simple
  diffusion.)
• Passive diffusion requires no ATP
• Uses transport proteins in membrane, which may
  have a subtle change in shape.
• Some of these proteins are gated channels where a
  stimulus causes them to open and close

51
Active transport (ATP) page 7 sg

• electron carrier protein animation - Google
  Search
• Animations

52
Define diffusion and osmosis. page 8 sg

• Diffusion is the passive movement of particles
  from a region of higher concentration to a region
  of lower concentration, as a result of the random
  motion of particles.
• Osmosis the passive moment of water molecules,
  across a partially permeable membrane, from a
  region of lower solute concentration to a region
  of higher solute concentration.

53

• Isotonic relative solute concentration of two
  solutions are equal
• Hypotonic relative solute concentration of one
  solution is less than another solution.
  Hypertonic relative solute concentration of one
  solution is greater than another solution.
• Solutions that cause cells to shrink are
  hypertonic solutions red blood cells placed in
  salt solution above 0.9 shrink and wrinkle, a
  condition called crenation.
•    

54
Endomembrane system page 8 sg

• Go to animation two for additional clarification
  Life  eLearning

55
endo and exocytose p 8 sg

• Vesicle Budding and Fusing
• Exocytosis move out
• Endocytosis move in

56
cell cycle involves interphase, mitosis, and
cytokinesis.

• G1 growth and preparation of the chromosomes
  for replication, there is a restriction point
  which once passed commits the cell to divide.
• S synthesis of DNA (and centrosomes) see DNA
  Replication
• G2 preparation for
• M mitosis
• When a cell is in any phase of the cell cycle
  other than mitosis, it is often said to be in
  interphase

57
Cell cycle

• The Cell Cycle

58
prophase, metaphase, anaphase, and telophase.)

• Mitosis
• Animations MITOSIS
• Animation Quizzes
• The Cell Cycle Mitosis Tutorial

59
Page 9 sg

• Produces genetically identical cells
• Needed for
• growth
• repair
• asexual reproduction

60
1.5 Cell Division

• 1.5.5
• Outline the differences in mitosis and
  cytokinesis between animal and plant cells.
• No centrioles in plant cells
• Cell plate formed in plants,
  membrane pinching in animal cells

61
1.5 Cell Division
62
Page 9 study guide

• tumours are the result of uncontrolled cell
  division and that these can occur in any organ.
• Video on Demand
• CancerQuest Cell Division Control of Cell
  Division