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Flashcards in The Cell Deck (18):
1

8 General Cellular Functions

1. Covering
2. Lining
3. Storage
4. Movement
5. Connection
6. Defense
7. Communication
8. Reproduction

2

3 Characteristics most cells have

-Plasma (cell) membrane
-Cytoplasm
-Nucleus

3

Plasma (Cell) Membrane

-function
-major constituents

-Phospholipid bilayer that is the extremely thin outer border on cell that selectively mediates what enters & leaves cell (gases, nutrients & wastes)
-Made of 2 components;
1. Lipids
-Phospholipids (75%): hydrophilic polar head & hydrophobic nonpolar tail - constitutes majority of lipid in cell membrane
-Cholestrol (20%): strengthens & stabilises membrane against extreme temp.
-Glycolipids (5-10%): Have carbohydrate molecules attached & facing out - forms the glycocaylx (involved in cell - cell recognition.
2.Proteins: Are complex molecules made of amino acid chains that give membrane functions
i)Integral: partially or fully embedded in membrane (e.g. channels)
ii) Peripheral: Proteins attached to surface - help w/ cell signalling
*Both can serve as enzymes

4

Cytoplasm - 3 parts

*Includes all materials between plasma membrane & nucleus
3 parts;
-Cytosol; Viscous, syrup-like fluid containing many different dissolved substances (e.g. ions, nutrients, proteins, aa, carbs)
-Inclusions: Large storage aggregates of complex molecules found in cytosol (e.g. melanin - pigment, glycogen - long chains of sugars in liver & skeletal muscles)
-Organelles: Membrane bound or non-membrane bound structures that have unique functions and activities

5

Smooth Endoplasmic Reticulum (SER)

-General features of ER
-Function of SER

*network of intracellular membrane w/ enclosed spaces called cisternae.
-walls have smooth appearance -lack of ribosomes.
Functions;
-Synthesis, transport & storage of lipids (e.g. hormones & steroids)
-Metabolism of carbohydrates
-Detoxification of drugs, alcohol & poisons

6

Rough Endoplasmic Reticulum (RER)

-Function

-Rough wall appearance due to ribosomes (protein synthesizers)
-continuous w/ SER
Synthesise, transport or store proteins for;
-secretion by cell
-Incorporation into plasma membrane
-creation of lysosomes

7

Golgi Apparatus

-Function
-Terminology for 2 regions

-stacked cisternae - lateral edges bulge, pinch off & give rise to small transport & secretory vesicles
-receives proteins & lipids from RER for modification, sorting & packaging
Receiving region = cis-face
Shipping region = Trans-face

8

Lysosomes

-Function
-Autophagy & autolysis

-Are vesicles generated by Golgi Apparatus (or membrane sacs filled w/ digestive fluid)
-Contain enzymes that are used to digest & remove waste products/damaged organelles w/n cell (Autophagy)
-Lysosomes release their enzymes that digest cell when dying (Autolysis)

9

Peroxisomes

-Vesicles smaller than lysosomes.
-Are membrane enclosed sacs that usu. contain large amounts of specific enzyme to break down harmful substances
-Use O2 & enzymes to catalase (detoxify) harmful molecules taken into cell
-hydroxide to H2O
-Are able to break down fatty acids

10

Mitochondria

-shape
-where ATP produced

-Bean shaped organelles w/ double membrane (inner forms cristae; has internal fluid matrix)
-Produce ATP (high energy containing molecule) ON THE cristae
-Referred to as the "powerhouses of the cell"

11

Ribosomes

-Free & fixed ribosomes

-Made up of small & large subunit - are dense cytoplasmic granules
-Responsible for protein synthesis
-Free Ribosomes: float unattached w/in cytosol - synthesize proteins for use in cells
-Fixed Ribosomes: attached to outer surface of RER; synthesis proteins for secretion, incorporation into plasma membrane or lysosomes

12

Cytoskeleton

-3 parts

-Is an organised network of protein filaments or hollow tubules throughout cell
-Provides structural support; facilitates cytoplasmic straming, organelle & cellular motility, transport of materials & chromosomal movement & cell division.
3 Parts;
1. Microfilaments: Actin protein monomers formed into filaments (used to maintain cell shape, aid in muscle contract. & separate dividing cells)
2. Intermediate filaments: Various protein components - provides structural support, stabilises cell junctions
3. Microtubules: Hollow cylinders of tubulin proteins; able to lengthen & shorten - support cell, hold organelles in place, maintain cell shape & rigidity, direct organelle movement w/in cell as cilia & flagella; move chromosomes @ cell division

13

Centrosome & Centrioles

Centrosome: Amorphous regionattached to nucleus; contains a pair of centrioles at right angles to each other
Centriole: Nine sets of microtubule triplets
-involved in organising microtubules
-attach to chromosomes during cell division - causes chromosomal migration

14

Cilia & Flagella

-Projections on the cell containing cytoplasm & microtubules capable of movement
-Cilia: On cells that move objects across their surface (i.e. cells of respiratory tree & oviduct)
-Flagella: longer, usu. singular, to propel a cell (e.g. sperm)

15

Microvilli

-Extensions of cell NOT capable of motion (altho. look like cilia are in fact much smaller)
-Purpose is to increase SA to increase absorption of food (found on surface of cells of small intestine)

16

Nucleus

-Chromatin vs. Chromosomes

-Control centre for cellular activity - controls protein synthesis which directs functional & structural characteristics of cell
-Contains DNA
Chromatin: unwound form DNA takes when not dividing
Chromosome: wound up form DNA takes when dividing

17

Nuclear Envelope, Nuclear Pores & Nucleolus

Nuclear Envelope: Double membrane structure that is the physical barrier between the nucleus to cytoplasm
-outer membrane continuous w/ ER
Nuclear Pores: Openings in nuclear envelope - is what allows passage of materials
Nucleoulus: spherical, dark staining, dense granula region w/in nucleus - responsible for making small & large subunits of ribosomes

18

Life Cycle of Cell

-Cell always in one of two stages:

1. Interphase: Maintenance phase between divisions where cell either prepares for division or undergoes normal activities. Is where cell spends majority of its time.

2. Mitotic Phase: When cell divides (Chromatin to chromosomes)