Cells Unit Cont’d

Proks,Euks, Cell Membrane S&F, Cell Transport, Cell Cycle

Prokaryotic vs. Eukaryotic Cells Characteristics

• Prokaryotes Eukaryote• Size of cell • 0.2-2.0 m m in diameter 10-100 m m in diameter • Nucleus • None True nucleus • Membrane-enclosed organelles • Absent Present; examples include• lysosomes, Golgi complex,• endoplasmic reticulum,• mitochondria & chloroplasts• Flagella • Consist of two protein building Complex; consist of multiple blocks microtubules • Cell wall • Often present; chemically complex When present, chemically simple • Plasma membrane • No carbohydrates and Sterols and carbohydrates that generally lacks sterols serve as receptors present

Proks. Vs. Euks. Cont’d• Cytoplasm • No cytosketeton or Cytoskeleton; cytoplasmic cytoplasmic streaming streaming • Ribosomes • Smaller size (70S) Larger size (80S); smaller size (70S) in organelles • Chromosome (DNA) arrangement • Single circular chromosome; Multiple linear lacks histones chromosomes with histones• Cell division • Binary fission Mitosis • Sexual reproduction • No meiosis; transfer of DNA Involves meiosis fragments only (conjugation)       

Comparing Plant vs. Animal Cells

Cell Membrane Structure

Membranes cont’d

• The role and significance of the amphipathic phospholipids

Membrane Proteins• Types of MPs

• IMPs and PPs

• Functions:

• Enzymes

• Hormone binding sites

• Channels for passive transport

• Pumps for active transport

• Electron Carriers

Types of Cell Transport – Passive Transport

Diffusion – the passive movement of particles from a region of higher concentrations to a region of lower concentration, as a result of random molecular motion

Role of membrane permeability

Simple vs. Facilitated Diffusion

• Exs. Of FD (Na+, K+ and Cl- during nerve cell activity)

OsmosisDifferent from diffusion across cell membranes because

water is a solvent.

• The direction in which water moves is due to the concentration of solutes rather than the conc. of water molecules

• Defined as - the passive movement of water molecules from a region of lower solute concentration to a region of higher solute conc across a selectively permeable membrane.

Active Transport• The movement of substances across

membranes and against their conc. gradient, using energy from ATP

• Ex. Na+ - K+ pump; proton (H+) pumps;

General Types of Transport Proteins

Vesicle Transport• Exocytosis –

• Endocytosis –

• R.M. Endocytosis –

•