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)

WWWhat’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