[1] REVIEW OF THE CELL

 CELL THEORY

• Cell is the most basic unit of life

• All living things are made up of cells

• Cells can only arise from previously living cells

TYPES OF CELLS

• prokaryotic

• eukaryotic

PROKARYOTIC

• No well-defined nucleus

• Bacteria

EUKARYOTIC

• Has a well-defined nucleus 

• The rest

CELL PARTS

• cytoplasm

• cell membrane

• cell wall

Cytoplasm

• Area between the nuclear and cell membranes 

Cytoplasm contains the fluid _

cytosol

__ are suspended in the cytosol

organelles

Organelles in the Cytoplasm include:

• Ribosomes

• Endoplasmic Reticulum (smooth & rough)

• Mitochondria

• Golgi apparatus

• Vacuoles

• Microbodies (peroxisome, lysosome)

• Cytoskeleton (Microfilaments, intermediate filaments, Microtubules)

• Cilia & Flagella

• Nucleus (nuclear envelope, chromatin, nucleolus)

Ribosomes

Protein synthesis

Endoplasmic Reticulum (E.R.)

Bridges the nuclear and plasma membranes

Smooth E.R.

production/modification of lipids and membrane assembly 

Rough E.R

Responsible for much of protein modification

Mitochondrion

• “Powerhouse” of the cell

• Contains enzymes catabolism of biomolecules and produce production of usable energy (i.e. ATP)

Golgi apparatus

• “Packaging counter”

• Secretes, modifies, and delivers products from the cell throughout it and outside

Vacuoles

Store water and waste materials within the cell

Microbodies

Small globe-shaped organelles that contain a high-concentration of enzymes

Microbodies: Peroxisomes

Breaks down H₂O₂ (peroxide) into water and oxygen

Microbodies: Lysosomes

• “Suicidal sacs”

• Elimination of unwanted waste

Cytoskeleton

• A network of fibers that solidify the cell’s framework 

• Support the cytoplasm and form centrioles, spindle fibers, cilia and flagella

Microfilaments

• Smallest components 

• Main reason of the cell’s shape

Intermediate filaments

• Slightly wider fibers 

• Strengthen the hold of the cytoskeleton

Microtubules

• Made of tubulin proteins

• Provide motility for substances around the cell cytoplasm (e.g. Cilia & flagella)

Cilia & Flagella

Responsible for the cell’s movement/locomotion

Nucleus

• Center of genetic activity 

• Contains nucleic acids

Nuclear envelope

Separates nucleus from cytoplasm; allows movement of materials in and out of nucleus

Chromatin

DNA regulates protein synthesis; the genetic or hereditary material

Nucleolus

Assembly site of large and small ribosomal subunits

Cell membrane

• A semi-permeable phospholipid bilayer made of polar (hydrophilic) heads and nonpolar (hydrophobic) tails enclosing the entirety of the cytoplasm

• Controls the entry & exit of substances; intercellular communication & identification; catalyzes chemical reactions,

Cell wall

• Extra layer of protection beyond the cell membrane 

• Absent in animals

cellulose

Cell wall: Made of __ in plants

chitin

Cell wall: Made of __ in fungi

various sugars

Cell wall: Made of __ in bacterial peptidoglycan

CELL CYCLE

Carefully regulated to allow effective maintenance and repair of body tissues, and to replace damaged, dead, and worn-out cells 

• Cyclin-dependent kinases (CDK) 

• Cyclins 

• Cyclin-CDK complexes 

• Tumor suppressors

CELL CYCLE is regulated by:

G1 (Gap) Phase

• Phase instantly after cell division

• The cell in this phase is newly created, and still producing organelles

S (Synthesis) Phase

• Synthesis of DNA

• Ensures that new cells still contain all previous genes

G2 Phase

Phase wherein the cell prepares for cellular division

interphase

G1, S and G2 phases are collectively called the _

M (Mitotic) Phase

Dividing phase, wherein the cell undergoes the actual process of division

Prophase

• First phase of mitosis

1. Compressing of chromatins into coiled chromosomes 

2. Disappearance of the nuclear wall 

3. Moving of organelles at the side

4. Development of spindle fibers, made of tubulin proteins

Prophase is marked by the following:

Prometaphase

• Nuclear membrane breaks apart and the chromosomes can attach to the spindle & microtubules and begin active movement

Metaphase

Chromosomes align at the middle at what is called the “metaphase plate” in a horizontal fashion

Anaphase

Spindle fibers pull the chromosomes apart into the spindle poles

Telophase 

Reverse of prophase

Telophase is marked by the following:

1. Chromosomes become thinner again turning into thread-like chromatins

2. The nuclear walls appear 

3. The organelles move normally around the cytoplasm of the new cell 

4. Spindle fibers disappear

biomolecules

The organelles and other components of the cell are primarily made of _

Biochemistry

study of the structure (atomic/chemical structure, cell structure), function (purpose of the biomolecule), and metabolism of biomolecules.

• Proteins

• carbohydrates

• lipids

• nucleic acids

Biomolecules include: