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Cell Structure and Function Cheat Sheet by

Anatomy and Physiology Lecture 2

Functions of Cells

Basic unit of life
Cell metabolism and energy release
Synthesis of molecules
Commun­ication
Reprod­uction and inheri­tance

Whole Cell Activity

A cells charac­ter­istics are determined by the type of proteins it produces
Proteins' function is determined by genetics
Inform­ation in DNA provides the cell with a cade for its cellular processes

Osmosis

What is it?
Diffusion of water across a cell membrane
Osmotic Pressure
the force required to prevent movement of water across cell membrane
A measure of the tendency of water to move by osmosis across a select­ively permeable membrane

Osmotic Solutions

Hypotonic Solutions
Hypertonic Solutions
Isotonic Solutions
- lower concen­tration of solutes outside cell
higher concen­tration of solutes outside cell
Equal concen­tra­tions of solutes
Higher concen­tration of H2O outside cell
higher concen­tration of H2O inside cell
Water doesn't move
H2O moves into cell
H2O moves out
Cell remains intact
LYSIS (burst)
Crenation (shrinks)

Cell Structures

Cytoplasm
- Location
Inside cell
- Charac­ter­istic
Jelly-like fluid
- Function
Give cell shape and hold organelles in place
Nucleus (not part of the cytoplasm)
- Location
Center of cell
- Charac­ter­istics
All cells contain nucleus at some point
- Function
Houses DNA
Nuclear Envelope
- Location: edge of nucleus
Nuclear Pores
- Location
Surface of nucleus
- Function
Where materials pass in and out of nucleus
Chromosome
- Location
Inside nucleus
- Charac­ter­istic
Made of DNA and proteins
- Function
Part of genetic makeup
Chromatin
- Location
Inside nucleus
- Charac­ter­istic
Loosely coiled chromo­somes
Nucleolus
- Location
in nucleus
- Function
produce ribosomes that are then transp­orted to the cytoplasm
Ribosome
- Location
attached to rough endopl­asmic reticulum (RER) or free-f­loating in cytoplasm
- Function
Produce proteins
RER (Rough Endopl­asmic Reticulum)
- Location
Cytoplasm
- Charac­ter­istic
Membranes with ribosomes attached
- Function
Site of protein synthesis
SER (Smooth Endopl­asmic Reticulum)
- Location
Cytoplasm
- Charac­ter­istic
membranes with no ribosomes
- Function
Site of lipid synthesis
Golgi Apparatus
- Location
Cytoplasm
- Charac­ter­istic
Closely, packed stacks of membranes
- Function
Collect, sort, package, and distribute proteins and lipids
Secretory Vesicle
- Location
Cytoplasm
- Function
Distri­butes materials out of cell
Lysosome
- Location
Cytoplasm
- Function
Enzymes that digest foreign material
Mitoch­ondria
- Location
Cytoplasm
- Charac­ter­istics
Contains folds (cristae)
- Function
Produces ATP
 

Main Components of a cell

Plasma or cell membrane
Organelles
Cytoplasm

Jobs of the Cell Membrane

1. Separate the inside from the outside of the cell
2. Enable the immune system to recognize the cell as self or non-self --> marker glycop­roteins or glycol­ipids
3. Attach cells together or to the extrac­ellular matrix --> adhesion proteins
4. Receive signals from outside the cell and transmit the signals to inside the cell --> receptor proteins
5. Select­ively transport substances from inside to outside the cell, or outside to inside the cell via transport mechanisms

Movement through the Cell Membrane

- Cell membrane select­ively determines what can pass in and out of the cell
- Enzymes, glycogen, and potassium are found in higher concen­tra­tions INSIDE the cell
- Sodium, calcium, and chloride are found in higher concen­tra­tions OUTSIDE the cell
- Nutrients must be able to enter the cell and waste products must be able to exit the cell
1. Directly through diffusion (passive):
O2 and CO2 (small molecules)
2. Facili­tated diffusion (passive) through membrane channels:
- proteins that extend from one side of the cell membrane to other
- Size, shape and charge (+/-) determine what can go through
- Ex. Na+ passes through Na+ channels
3. Carrier molecules:
- bind to molecules, transport them across, and drop them off
4. Vesicles:
- Can transport a variety of materials
- Fuse with cell membrane

Endocy­tosis

What is it?
Process that brings materials into cell using vesicles
1. Phagoc­ytosis
Cell eating (solid particles)
2. Pinocy­tosis
Cell drinking (liquid particles)
3. Receptor mediated endocy­tosis

Cytosk­eleton

What is is?
- Cells framework
- Made of proteins
Functions
- Provide support
- Hold organelles in place
- enable cell to change shape
Types of Cytosk­eleton
Microt­ubules
- Largest diamete
- Provide structural support
- Form cilia and flagella
Interm­ediate filaments
- Medium diameter
- maintain cell shape
Microf­ila­ments
- Smallest diameter
- Involved in cell movement

Cell Division

- Formation of 2 daughter cells from a single parent cell
- Uses mitosis and meiosis
- each cell (except sperm and egg) contains 46 chromo­somes (diploid)
- Sperm and egg contain 23 chromo­somes (haploid)
Mitosis
- Cell division that occurs in all cells except sex cells
- Forms 2 daughter cells
1. Interphase: 46 chromo­somes
2. Prophase: Chromo­somes doubled to 92
3. Promet­aphase: Nucleus dissolves and microt­ubules attach to centro­meres
4. Metaphase: Chromo­somes align at middle of cell
5. Anaphase: Separated chromo­somes pulled apart
6. Telophase: Microt­ubules disappear cell division begins
7. Cytoki­nesis: Two daughter cells formed each with 46 chromo­somes
 

Cell Membrane

Funtions:
- Selective barrier
-Encloses cytoplasm
Extrac­ellular
Material outside of cell
Intrac­ellular
Material inside cell membrane
Fluid Mosaic Model
a 2D liquid in which phospo­hol­ipids and proteins diffuse easily
Made of phosph­olipids and proteins
phosph­olipids form a double layer or bilayer
Polar Region
- "­hea­ds"
- hydrop­hilic
- exposed to H2O
Nonpolar Regions
- "­tai­ls"
- hydrop­hobic
- away from H2O
cell membrane consists of phosph­oli­pids, choles­terol (for strength and flexib­ility), and proteins

Diffusion

What is it?
movement of molecules from areas of high to low concen­tration
Solution
solid, liquid, or gas that contains one or more solutes
Solute
Substance added to solvent that dissolves
Solvent
Substance such as H2O that solute is being added to
Is energy required?
no

Mediated Transport Mechanisms

Facili­tated diffusion
- diffusion with aid of a carrier molecule
- requires no ATP
- passive transport
Active transport
- moves substance from low to high concen­tration
- required ATP
Ex. Sodium­-po­tassium pump
Cotran­sport
- a diffusing substance moves in same direction as a transp­orted substance
Counte­rporter protein
- a diffusing substance moves in direction opposite to that of transp­orted substance

Microt­ubules of the Cytosk­eleton

Centriole
- Composed of 9 microt­ubules
Centrosome
- 2 centrioles oriented perpen­dicular to one another. Plays a role in mitosis
Flagella
- Location
Cell surface
- Charac­ter­istic
1 per cell
- Function
move cell, Eg. Sperm
Cilia
- Location
Cell Surface
- Charac­ter­istic
Many per cell
- Function
Move materials across cell's surface
Microvilli
- Location
Cell Surface
- Charac­ter­istic
Shorter than cilia
- Function
Increase surface area

DNA

Double helix
Deoxyr­ibo­se-­pho­sphate backbone
Nucleotide base pairs
Backbone = sugar (ribos­e-p­hos­phate)
Gene Expression
- inform­ation in DNA directs protein synthesis
- nucleotide sequence of a gene determines amino acid sequence of specific protein
- Enzymes regulate chemical reactions
- Uses transc­ription and transl­ation

Flow of Genetic Inform­ation

Central Dogma
DNA - transcribe - RNA - translate - Protein
Transc­ription
- Process by which DNA is read
- Occurs in the nucleus
- Produces mRNA
- mRNA contains codons
- Codons: set of 3 nucleotide bases that code for a particular amino acid
Transl­ation
- Process by mRNA is converted into amino acids (polyp­ept­ides)
- Produces proteins
- Codons pair with anticodons
- antico­dons: 3 nucleotide bases carried by tRNA
 

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  • Published: 20th January, 2018
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