Cells

CELL STRUCTURES AND CELL FUNCTIONS 


Learning outcomes:
- Explain that the basic unit of all living things is the cell.
- Identify structure and state the function of the main organelles in the cell such as nucleus, nucleus membrane, chromatin, cytoplasm, vacuole, mitochondria, ER, ribosomes, Golgi apparatus, lysosomes, chloroplast, cell wall.
- Identify the main organelles from diagrams
- Compare and contrast plant and animal cells.

Cell Theory
- All living things are made out of cells
- Cells are the smallest working units of all living things.
- All cells come from re-existing cells through cell division.

Definition of cell
A cell is the smallest that is capable of performing life functions.

Example of cells
- Amoeba Proteus
- Plant stem
- Bacteria
- Nerve cell
- Red blood cell

Two types of cells
- Prokaryotic
- Eukaryotic

Prokaryotic
- Do not have organelles (specialized structure in cells) surrounded by membranes
- Few internal structures
- One celled organisms eg. Bacteria

Eukaryotic
- Contain organelles surrounded by membranes
- Most living organisms eg plant, animal, fungi                                              

Cell wall
- Most commonly found in plant cells and bacteria
- Surrounds the cell membrane
- Rigid structure that maintains the shape, supports and protects cells
- Permeable to small molecules and small proteins only.

Surrounding the cell

Membrane
- Selectively permeable membrane of cell that controls movement of substances in and out of the cell
- Do NOT say semi permeable, the correct term is selectively permeable or partially permeable

Nucleus
- Contain chromatins that control cell activities
- Chromatin contain DNA which is genetic material
- DNA contain instructions for traits and characteristics and to carry out the cell’s function
- Separated from cytoplasm by nuclear membrane

Cytoplasm
- Gel like mixture
- Surrounded by cell membrane
- Contains organelles

Mitochondria
- Referred to as the “powerhouse” of the cell
- The food with eat is transformed into energy (ATP) for the cell and our bodies
- Produces molecules

Endoplasmic Reticulum
- An interconnected network of tubes and vesicles
- Synthesis of proteins, fats, steroid
- Transports materials around in a cell
- Smooth type: lack ribosomes
- Rough type: ribosomes embedded in surface

Ribosomes
- Each cell contains thousands of ribosomes
- Make proteins
- Found on endoplasmic reticulum and floating throughout the cell

Golgi Bodies
- Works closely with the ER
- Primary Function is to process and package complex molecules such as proteins and fats that are made by the cell
- Brings these products to the surface of the cell where they can be secreted
- Other secretions include hormones, antibodies and enzymes
- Use the term: Golgi apparatus

Lysosome
- Contain digestive enzymes
- Digest excess or worn-out organelles, food particles and engulf bacteria or viruses
- Also help repair worn-out plasma membrane
- They also provide sugars, amino acids and bases which are the foundation of macromolecules
- Cell breaks down if lysosome explodes

Harvard VPA screenshot

Dr Dede

Classification- continued

Rules for naming organisms
- The International Code for Binomial Nomenclature contains the rules for naming organisms
- All the names must be approved by International Naming Congress
-       This prevents the duplication of names

Classification groups
- Taxon (taxa-plural) is a category into which related organisms are placed
- There is a hierarchy of groups (taxa) from broadest to most specific
- Domain, Kingdom, Phylum, Class, Order, Family, Genus, species
Domains
- Broadest, most inclusive taxon
- Three domains
- Archaea and Eubacteria are unicellular prokaryotes (no nucleus or membrane-bound organelles)
- Eukarya are more complex and have a nucleus and membrane-bound organelles (We humans belong here:D)

Taxons
- Most genera contain a number of similar species, with the exception of Homo that only modern humans
- Each successive classification category or taxon contains more different types of organisms than the preceding category

King              Kingdom
Phillip            Phylum
Came            Class
Over             Order
For               Family
Gooseberry    Genus
Soup            species

Spheniscidae^^

Classification

Biodiversity

-There are 13 Billion known species of organisms

-This is about 5% of all organisms that ever lived 

What is classification?

-Classification is the arrangement of organisms into orderly groups based on their similarities

-Classification is known as taxonomy

-Taxonomists are scientists that identify and name organisms

Benefits of Classifying

-Accurately and uniformly names organisms 

-Prevents misnomers such as starfish and jellyfish that aren’t really fish

-Uses same language (Mostly Latin or sometimes Greek) for all names

Naming Organisms

-Two-word name (Genus and species)

Eg. Humans: Homo Sapiens

Problems in Classifying Organisms

-species have inter breeding

Standardized Naming

-Binomial nomenclature used

-Genus species

-Latin or Greek

-Italicized in print

-Capitalise genus, but not species

-Underline when writing

Eg. Homo sapiens

Canis familiaris. ITS SHO FLUFFAY XD

Mealwormsss

Aim: To find out the reactions of mealworms in the presence/absence of light
Hypothesis: The mealworms will move away from the light
Materials: torchlight, opaque box, timer

Procedure:
 1. Place the mealworms into the box
2. Shine the torchlight into a part of the box of mealworms
3. Start the timer and stop after 10min
4. Observe the reaction and position of the mealworms, whether they are on the bright side of the box where the torch is being shined, or the darker part with no light

Variables:
Independent Variable: The presence of light
Dependent Variable: The reaction of the mealworms
Constant Variable: The number of mealworms used, the duration of the experiment

Observations:

Primates

We watched a video about gorillas in class recently and these are my observations of them

- They're feet have a gap between the big toe and the other toes
- They usually walk on all four limbs, only sometimes on their two feet without using their arms
- After running for awhile, they get up on their feet only and pump/hit their chest
- They rest on the back of their hands while walking on all fours
- Their arms are longer than their feet
- They are hunched over

These are some questions I have on them

- Why do they pump/hit their chest?
- Why do they move on all fours sometimes, and on two feet at other times?
- Why is there a large gap between their big toe and the rest?
- Why is their skin rough?
- How long can primates walk only on their feet?
- Can primates swing on trees?

Is it Alive?

Link:  http://goo.gl/g35sa