Plasma Membrane of aveolar sac 7-2 and 7-3: Plasma Membrane and Cell Structures But first...

Let’s Review  What is cell theory?  Light microscopes vs. electron microscopes  Prokaryotic vs. eukaryotic

Basic Cell Structures  Cell Membrane  Cell Wall  Nucleus  Cytoplasm

VOCABULARY  Chromatin  Chromosome  Nucleolus  Nuclear envelope  Cytoskeleton  Microtubule  Microfilament  Endoplasmic Reticulum  Golgi Apparatus  Lysosome  Vacuole  Chloroplast  Mitochondrion  Ribosome

Plasma Membrane  Boundary between cell and environment

 Allows for nutrients to enter and exit cell  Maintains cell’s homeostasis Nerve cell plasma membrane

How does plasma membrane maintain homeostasis?  Selective permeability  Allows certain molecules in while keeping others out  Water usually enters/exits cells freely  Ion (e.g. Ca and Na) allowed in at certain times

Structure of PM  Composed of 2 layers of phospholipids (oh no…not again!)

 Phospholipids  Hydrophilic head (outside/inside of cell)  Hydrophobic tail (inside of membrane)  These form a barrier and do not allow water-soluble molecules to pass through

Fluid mosaic Thin flexible layer

What else is in the plasma membrane?  Cholesterol  Aids in phospholipid stability by preventing them to stick together  Proteins  Transport proteins Help with allowing nutrients come in and wastes exit cell  Cell identification  Cell structure and support

Cytoplasm  Material inside the cell membrane but not including the nucleus Cytoplasm

Found in some cells, including plants, algae, fungi, and nearly all prokaryotes (NOT animal cells) Cell Wall

Surrounds the cell membrane (allows water and gases to pass through) Provides support and protection for the cell

Nucleus  Nucleus (pl. Nuclei)  Large structure that contains the genetic information (DNA) and controls the cell’s activities

DNA contains the instructions for making proteins *the nucleus is important because making proteins is one of the main functions of cells Protein Synthesis

CHROMATIN & CHROMOSOMES: Chromatin: DNA chain wound around a protein  visible DNA (looks granular—is spread throughout the nucleus) Chromosomes: when a cell divides, chromatin continues to condense into these structures  these are distinct structures

NUCLEOLUS: Dense region inside most nuclei (looks darker) Ribosome assembly begins here NUCLEAR ENVELOPE: Double-membrane layer which surrounds nucleus Thousands of pores allow material into and out of the nucleus

Nucleus

Cytoskeleton Network of protein filaments that helps the cell maintain shape & move around Help in cell division!!!

Ribosomes  Ribosomes are made of RNA & protein  Proteins are assembled (made) here  Proteins are produced following the specific code in DNA

ENDOPLASMIC RETICULUM (ER): Some proteins are modified Components of the cell membrane are assembled ROUGH ER: ribosomes on the ER make proteins & these new proteins move into the ER where they may be chemically modified SMOOTH ER: no ribosomes; contains specialized enzymes that perform specific tasks (ex: make lipids)

WWWh at’s missing ?? W

Real Picture… “Fake” Picture

GOLGI APPARATUS: Proteins produced by Rough ER ribosomes move into these sac-like structures Enzymes attach carbohydrates & lipids to the proteins These proteins are then sent to their final destination

Lysosomes  Filled with digestive enzymes: break down carbo’s, lipids, & proteins for use by cell  Break down old cells

Vacuoles  Store materials like water, salts, proteins, & carbo’s for the cell  Large central vacuole in plants is the reason plants are rigid!

PLANTS ONLY! Use energy from sun to make glucose (photosynthesis) Visible stacks of membranes

Mitochondria Release energy from food—cell uses that energy to power growth, movement, etc.

Cilia and Flagella  Aid in locomotion or feeding