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Lecture 2a:Cells
Lecture 2a:Cells
Plasma Membrane
Forms the boundary of the cell
It is the ‘gatekeeper’ for the cell
Here is a simple bilayer
Plasma Membrane
There are proteins imbedded in the membrane - these are the keymasters
Membrane ProteinsThere are several different functions that the membrane proteins perform for the cell - write in the definitions!
Channel
Transport
Recognition
Membrane Proteins
There are several different functions that the membrane proteins perform for the cell - write in the definitions!
Receptor
Signal molecule
Enzymatic
Junction
Eukaryotic Cells
Have a membrane-bound nucleus
Organelles
The ‘organs’ of the cell- the organelles concentrate the molecules needed for various functions in one place
NucleusNucleus: where the DNA is, the CEO of the cell
Chromatin: ‘uncoiled’ DNA- long strands of DNA, what condenses into chromosomes during cell division
Some RNA and protein are in chromatin too
Nucleus and RibosomesMessenger RNA (mRNA) takes the genetic information from the DNA to the ribosomes
mRNA is made in the nucleus
Ribosomal RNA (rRNA) forms part of the ribosomes
rRNA is made in the nucleolus
Nucleus
The nucleus has a double membrane- the nuclear envelope, with pores that allow various RNA/ proteins in and out.
Anatomy of the Nucleus
Ribosomes
The site of protein synthesis - receives mRNA from nucleus
Has two subunits: large and small
Some free-floating, some attached to endoplasmic reticulum
Proteins made on ER move inside it; where finalization takes place
Endomembrane System
The membranous parts of the cell that help to organize it
Includes: nuclear envelope, ER, Golgi appratus, vesicles
Vesicle: membranous sac
Endoplasmic ReticulumThe factory of the cell
Rough ER: Makes proteins, studded with ribosomes
Smooth ER: makes lipids, specific to cell type
ex: smooth ER in testes makes testosterone
Both make transport vesicles
Golgi Apparatus
It is the transport station of the cell
Receives transport vesicles from ER
Modifies proteins or lipids
Sorts and organizes products for shipment, either to cytoplasm or out of the cell
Lysosomes
The body’s recycling plant
Specialized vesicles that digest waste or unused molecules or cell parts
Contain enzymes
Vacuoles
Super-size vesicles with specialized functions
Water in plant cells
Color, toxins in plant cells
Fat cells store lipids in vaculoles
Energy Organelles
Chloroplasts: plants
Mitochondria: plants and animals
Things common to both:
Bound by double membrane, then another membrane inside
Have their own DNA and ribosomes; theory is that they are derived from bacteria that invaded eukaryotic cells
Chloroplasts
Chloroplasts: Where plants do their magic! - Turn sunlight into glucose
This is photosynthesis
Chloroplasts
Parts to know:
Stroma: Inner space - Where enzymes that make glucose are
Thylakoids: disklike sacs, which when stacked together are called
Granum - this is where pigments capture sunlight
MitochondriaVery small- but very important!
Make ATP, the energy molecule, via
Cellular Respiration
Can move from place to place as needed
adenosine triphosphate: ATP
Mitochondria
Parts to know:
Matrix: inner area, contains enzymes to break down carbohydrates
Cristae: highly folded inner membrane
Where ATP is actually made
Structure and MotionCytoskeleton: provides structure
Microtubules: small hollow cylinders
Provide structure and pathways
Intermediate filaments
Support between nucleus and membrane
Actin Filaments
Form a web inside membrane
Structure and Motion
Motor Proteins
Three proteins used: myosin, kinesin, dynein
Myosin moves entire cell in some way
Others attach with organelles to move them around the cell
Structure and Motion
Cilia and Flagella
Used to move the entire cell around
Single-celled organisms
The Outer Layer
Cell Wall
All plant cells have this - where the cellulose is
Gives the plant its strength, both through structure and by joining to other cells
The Outer Layer
Extracellular Matrix
In animal cells, Provides stucture to animal
Where you find collagen and elastin
Can be very strong or rather weak, depending on the tissue
The Outer LayerJunctions
Adhesion: Creates sturdy but flexible sheet of cells - like in the bladder
Tight: plasma membranes attach to each other - cells that are barriers
Gap: allows cells to communicate, it is the joining of two identical membrane channels - what allows heart cells to contract as one unit