The Cell and organelles – Basic Unit of Life.pdf

Cells and organelles

1. The Cell –
Basic Unit
of Life
Grade 10 Life Sciences

2. CELL
NON-LIVING
Cell wall
LIVING
Protoplasm
Cytoplasm
Cell membrane Organelles
Nucleus

3. Cell Structures

4. CELL WALL
•Not considered part of living protoplasm
•Formed by the cell membrane on the outside
•Consists of cellulosewith other carbohydrates:
•Primary cell wall –pectin(sugary substance)
•Secondary cell wall –lignin(woody substance) or suberin
(waterproof substance)
•Functions include support, shape and protection

5. Plasmodesmata –thin cytoplasmic
threads connecting adjacent cells
can occur through…
Pits–gaps in the cell wall

6. CELL MEMBRANE
•Very thin, outer living boundary (part of protoplasm)
•Controls the movement of substances into and out of the cell =
semi/selectively permeable
•‘Fluid Mosaic Model’ used to describe structure of membrane

8. Fluid Mosaic Model:
•Cell membrane consists of a double layer of
phospholipidmolecules that consist of two parts:
-The head(phosphate) faces outwards & attracts water
(hydrophilic) as it is polar
-The tail(2 fatty acid chains) faces inwards & repels water
(hydrophobic) as it is non-polar
•Embedded in & on top of these layers are protein
molecules some of which are carrier & channel
proteins (glucose, amino acids, salts, nucleic acids)
•The cell membrane is NOT static as all the
molecules move around –hence ‘fluid’

10. NUCLEUS
•Controls and directs all cellular functions
•Passes hereditary characteristics from one generation
to the next

11. Diagram of a nucleus
Draw the
diagram
following the
biological
drawing rules!

13. MITOCHONDRION
Plural = mitochondria
•Sites of cellular respiration
•Provides the cell with energy (ATPis the energy-carrier)
•Adaptations:
•Has many respiratory enzymes to speed up the process
•Inner membrane is foldedto fit a lot of respiratory enzymes

14. Diagram of a mitochondrion
Draw the
diagram
following the
biological
drawing rules!

16. ENDOPLASMIC RETICULUM
•Membranous network that forms a
continuous system of canals
throughout cytoplasm
•Connected to the cell membrane &
nuclear membrane; associated with
the golgiapparatus
•Two types:
•Rough ER has ribosomes
•Smooth ER has no ribosomes

17. •The ER transports substances
from one part of the
cytoplasm to another
•It increases internal surface
areaof the cell
•It plays a role in protein
synthesis due to ribosomes

20. RIBOSOMES
•Small, spherical structures
•Consist of RNA& proteins
•Occur in the ER, mitochondria,
chloroplasts & in cytoplasm
•Sites of protein synthesis –amino
acids join to form a protein

22. GOLGI APPARATUS
•A.k.a. golgibody or dictysome
•Consists of stacks of hollow, flat
membrane sacs known as cisternae
•Produces & processes secretions
(mucus, saliva)
•Plays a role in formation of lysosomes
•Prepares proteins for transport to other
parts of the cell

24. PLASTIDS
•Organelles that occur only in plant cells
•Three types:
1.Chloroplasts
2.Chromoplasts
3.Leucoplasts

25. CHLOROPLASTS
•Occurs in photosynthesizing parts
of plants (leaves)
•Green pigment chlorophyll
absorbs light
•Sites of photosynthesis

26. Diagram of a chloroplast
Draw the
diagram
following the
biological
drawing rules!

29. Spirogyra –type of algae

31. CHROMOPLASTS
•Plastids that contain pigments known as carotenoids
•Responsible for yellow, orange, & red of flowers, leaves
& fruits

35. LEUCOPLASTS
•Colourlessplastids
•Occurs in cells that store food in an insoluble form:
•Starch -amyloplasts
•Lipids
•proteins

37. VACUOLES
•Fluid-filled compartments in the
cytoplasm
•Enclosed by a semi-permeable
membrane –tonoplast
•The fluid –cell sap, contains water
& dissolved substances
•Plant cell vacuoles are large &
prominent
•Animal cell vacuoles are small or
absent

39. In plant cells…
•Cell sap in the vacuole causes a pressure against the cell
wall that gives the plant cell rigidity –turgor pressure

40. Other types of vacuoles
1.Contractile vacuoles
•Occurs in unicellular organisms
•Functions in osmoregulation (water balance)
2.Lysosomes
•Occurs only in animal cells
•Filled with digestive enzymes
•Functions in protection of cell & intracellular
digestion

41. 3.Phagosomes
(food vacuoles)
•Occurs in unicellular
organisms
•Functions in digestion &
storage of food
•Fuses with lysosome to digest
4.Vesicles
•Transports substances from
Golgi body to other parts
inside or outside of cell

42. CENTRIOLES
•Cylinder-shaped organelle made of
microtubules
•Only occurs in animal cells
•Found in an area near the nucleus
called the centrosome
•Two centrioles lie at 90°angle to
each other
•Functions in the formation of
spindle during mitosis (cell division)

44. Plant Cellvs. Animal Cell

45. PLANT ANIMAL
Have plastids Do not have plastids
Have cell wall (made of cellulose) Do not have cell wall
Have large, central vacuole Have small, temporary vacuoles (if any)
May have plasmodesmata Do not have plasmodesmata
Do not have centrioles Have paired centrioles within centrosome
Generally have a fixed, regular shape Generally have an amorphous, irregular shape
Table comparing the difference between plant and animal cells

46. MOVEMENT OF SUBSTANCES
•Cells and the fluid that surrounds them are mostly water,
with other substances dissolved in them
•A soluteis a substance that is dissolved in a solvent
Eg.The salt
•A solventis a liquid that can dissolve substances
Eg.The water
•A solutionis a liquid that has substances dissolved in it.
Eg.The salt water

47. Substances move across cell membranes by
passive transport(no energy) or active transport (takes energy)
•Types of passive transport:
1.Diffusion
2.Facilitated Diffusion
3.Osmosis
•Types of active transport:
1.Using ion pumps
2.Bulk Transport

48. Diffusion
•Diffusion is the movement of dissolved solutes or gases from
an area of high concentration to an area of low concentration
(down a concentration gradient)
•It occurs because molecules always spread out evenly into
the available space
•Small molecules such as Oxygen and Carbon Dioxide can
easily cross the cell membrane in this way
•This process is passive, no energy required

49. WATER
Molecules of solute
Membrane (cross section)
Net
diffusion
Net
diffusion
(a) Diffusion of one solute
Equilibrium
The diffusion of solutes across a membrane:

50. (b) Diffusion of two solutes
Net diffusion
Net diffusion
Net diffusion
Net diffusion
Equilibrium
Equilibrium

51. Facilitated Diffusion
•Large molecules (eg.glucose) and charged molecules (ions)
cannot easily pass through the cells phospholipid bilayer
•These molecules diffuse across the transport proteins

52. Active Transport
•Active transport is the movement of dissolved solutes
across a membrane against a concentration gradient
(moving from low to high concentration).
•This process is active & requires energy in the form of ATP.

54. EXTRACELLULAR
FLUID
H
+
H
+
H
+
H
+
Ion Pump
+
+
+
H
+
H
+
+
+
H
+
–
–
–
–
Chemical
energy
CYTOPLASM
–
1. Ion pumps
Cells can use chemical energy to force particles
through protein pumps in the membrane

55. •Very large molecules, such as carbohydrates and
proteins, cross the membrane in bulk using vesicles
•Bulk transport requires energy
•Two types of Bulk transport:
•Exocytosis: transport vesicles travel to the cell membrane,
fuse with it, and release their contents
•Endocytosis: the cell takes in macromolecules by forming
vesicles from the cell membrane
2. Bulk transport

56. Which diagram
shows exocytosis
and which shows
endocytosis?
vesicle
2.
1.

57. Review: Passive and Active Transport

58. Osmosis
•Osmosis is the diffusion of water across a selectively
permeable membrane
•Just like other types of diffusion, a substance moves from
an area of high concentrationto an area of low
concentration
•The only difference is that this time the substance is water
•Therefore, water diffuses across a membrane from the
region of lower solute concentrationto the region of higher
solute concentration

60. Because of osmosis, a cell may either gain or lose water
depending on the environment it is in.
If a cell is in a:
•Isotonicsolution: Solute concentration is the same as that
inside the cell; no net water movement across the cell
membrane
•Hypertonicsolution: Solute concentration is greater than
that inside the cell; cell loses water
•Hypotonicsolution: Solute concentration is less than that
inside the cell; cell gains water
Whenever possible, water moves from a
hypotonic solution to a hypertonic solution

61. Solution and cell
are Isotonic
(a) Animal
cell:
(b) Plant
cell
H
2O
Burst
H
2O
Turgid (normal)
H
2O
H
2O
H
2O
H
2O
Normal
Solution is
Hypotonic
Flaccid
H
2O
H
2O
Shriveled
Shriveled
Solution is
Hypertonic

63. Did you know
that reverse
osmosis is used
as a desalination
method to purify
sea water?

64. Search for video “Reverse Osmosis Process”or copy link below
Youtubelink: https://www.youtube.com/watch?v=4RDA_B_dRQ0