Chapter 4 learning objectives

Light microscope

2D, uses light, general cell viewing

Transmission electron microscope

2D, uses electron beam, view internal structures

Scanning Electron Microscope

3D, uses electron beam to view, surface structure, digital image

human cells size range

Microscopic to human height (.1nm-10m)

some cell shapes

Spherical, cube like, cylindrical, disc shaped, and irregular

Plasma membrane

Barrier, separates internal cell from IF

Nucleus

Largest, houses DNA

Cytoplasm

Content btwn PM and nucleus

MBO

Membrane enclosed; made of ER, Golgi, lysosome, peroxisome, and mitochondria

NMBO

Not enclosed; made of protein & ribosomes

Cell inclusions

Not organelles; clusters; are pigments and nutrient storage

Cells function

Maintain shape; obtain nutrients; form chemical structures; dispose of waste

Lipid components of the PM and their functions

Phospholipids-keeps cytosol in cell

Cholesterol-strengthens and stabilize

Glycolipids-recognition; attatched carb group

Integral proteins in the PM

Embedded in; extend across

Peripheral proteins

Not embedded; loosely attached; anchored to the integral protein

Major roles of the MP (ITRACE)

1.transport 2.receptors bind ligands 3.identity marker communicate cells place 4.enzymes digest 5.anchoring sites secure cytoskeleton 6.cell adhesion proteins attachment site

Diffusion

Movement of solutes down their concentration gradient

Simple diffusion

Molecules that are SMALL and NONPOLAR move out of a cell down their concentration gradient

Facilitated diffusion

Must be assisted by PM down their concentration gradient

Ósmosis

Water movement through SP membrane

The relationship of osmosis and tonicity

A solution changing tone by osmosis is tonicity

PAT

Uses energy from ATP to move substance up CG

SAT

One substance moves down its CG to move a dif substance up its GC (seesaw)

Exocytosis (type of vesicular transport)

Large amounts of substances secreted from the cell

Endocytosis (another form of vesicular transport)

Intake large substances into the cell

What’s the difference btwn exocytosis and endocytosis

Secretes versus intakes

Phagocytosis (type of endocytosis)

Cellular eating

Pinocytosis (form of endocytosis)

Cellular drinking

Receptor mediated endocytosis (form of endocytosis)

Molecules bind to cell surface receptors

RMP

When a cell is at rest (has potential)

RMP

Established by K+ leaving (drains) and Ma+ entering (charges) via leak channels then the pump “recharges” for balance

K+ in RMP (moves out)

K+ leaves through leak channels due to chemical gradient then movement is slowed by electric gradient then creates RMP, sets the baseline

Na+ in RMP (moves in/raises to more positive)

Na+ enter nerve cells via leak channels driven by chemical and electrical forces, fewer Na+ channels lowers RMP

What’s the difference btwn K+ and Na+ in RMP

(-90)K+ has lots of leak channels and is the initial factor so it sets the baseline at a lower set value (-70)Na+ has fewer Leak channels resulting in higher net value of RMP

The balance of RMP

Na+/K+ pumps keep the RMP stable moving three Na+ out and two K+ in

Communication through direct contact is

Identity markers on cells

Channel linked receptors

Permit ion passage

Enzyme linked receptors

Are protein kinase enzymes and are activated directly to add a phosphate to other enzymes

G protein coupled receptors

are protein kinase enzymes and activated indirectly through the G protein

ER-MBO-structure

-Long tube structure with one continuous lumen (hollow)

Rough ER-MBO function

Producing, transporting, and storing proteins

Smooth ER-MBO function

Synthesis, transport, storage of lipids, metabolism, detox of drugs, alcohol, and poison

Gogli-MBO

Cisface-receiving transface-shipping structure- several flattened sacs function-modify, package, and sort proteins

Lysosomes-MBO

Structure-small, spherical sacs formed from the golgi function-digestion

Peroxisome-MBO

Structure-spherical sacs that contain over 50 enzymes function-digestion and synthesis

Endomembrane system-MBO-includes the gogli, vesicles, lysosomes, and peroxisomes, PM, and nuclear envelope

The movement of substances btwn MBO listed by vesicles, include all MBO except mitochondria

Mitochondria-MBO

Structure-Oblong shaped with double membrane & inner folds (cristae) function-powerhouse; turn food into energy

Ribosome-NMBO

Structure-large subunit and small subunit w/ each made of protein & RNA function-protein synthesis

Centrosome-NMBO

Structure-Up and down cylyndrical centrioles surrounded by protein with no shape Function-organizing microtubules in the cytoskeleton, cellular division

Proteasomes-NMBO

Structure-large barrel shaped protein Function-digest cell proteins

Cytoskeleton-NMBO

Structure-the framework Function-supports the cells body

Cilia-MBO

Structure-small hairlike projections extended out function-moves mucus out

Flagella-extension of cilia-MBO

Structure-One Longer and wider hairlike projections extended out Function-help propel a cell(sperm)

Microvioli-extension of cilia-MBO

Structure-Thin microscopic extension of the PM shorter and narrower densely packed Function-provides more PM surface area for transport

differences of Cilia, Flegala, and Microvilli

-multiple, small

-one long wide
-shorter multiple microscopic projections

Compare tight junction, Desmosomes, and Gap junctions

-seal spaces to prevent leaks

-anchor cells for strength

-allow passage of ions for communication

Nuclear envelope

Structure and function- separates the cytoplasm from the nucleoplasm controls the movement of materials btwn them

Nucleolus-NMB

Structure-dark staining spherical

Function-producing subunit if ribosomes

Relationship btwn DNA, Chromatin, and genes

in non dividing cells DNA is chromatin which is a loose structure allowing gene access

Required structures for transcription

DNA, ribonucleotides, and RNA polymerase

Three steps of transcription

Initation-DNA opens and RNA polymerase attaches, elongation-RNA polymerase copies DNA into MRNA, and termination-mRNA is finished and released

Structures for translation

Occurs at ribosomes; requires both messenger RNA and transfer RNA; Amino acids used to produce new protein molecules

Three functional forms of RNA

mRNA-messenger

tRNA-transfer

rRNA-ribosomal

Codon

A three letter genetic code word to signal stop

Sequences- AUG (start) UAA(stop) UUU(sense)

Three steps of translation

Initiation(starting) Elongation (building) termination(finishing)

Why dna is the cells control center

Holds the blueprint for making proteins

Chromatin versus chromosomes

Loose and unwound(interphase)- highly condensed tightly packed(mitosis)

The cell cycle summary

Interphase-the prep,

G1 phase- cell grows and makes copies,

S phase-copies DNA,

G2 phase-grows more and revises cell for error during S Phase, and

Mitotic phase-split and packs into chromosomes

Main event of mitotic phase

Mitosis-divides DNA

Prophase-Packs into chromosomes

Metaphase- line up in middle of cell

Anaphase- pulled apart to opposite sides

Telophase-two new nuclei form arriving DNA

Cytokinesis-divides the cell into two

Apoptosis

Programmed cell suicide; the cell shrinks, DNA breaks down, the cell bubbles, cell breaks, immune cells clean up (used for viruses)