Cell Structure and Function Attributes of cells A

Cell Structure and Function

Attributes of cells A. Plasma membrane B. DNA C. Cytoplasm D. Obtain energy and nutrients from their environment

Cell Size 1. 1– 100µm 2. Why is there a limit to cell size? a. Surface-to-volume ratio b. Distance from surface to center

tallest trees adult human chicken egg frog embryo most eukaryotic cells mitochondrion most bacteria virus proteins diameter of DNA double helix atoms

Cell types Prokaryotic—no nucleus, circular DNA, ribosomes Eukaryotic—larger, nucleus, linear chromosomes, membranous organelles

Prokaryotic Cells ¢ ¢ Have no membrane-bound organelles Include true bacteria On earth 3. 8 million years Found nearly everywhere l l Spores in each breath; intestines Naturally in soil, air, hot springs

nucleoid (DNA) ribosomes food granule prokaryotic flagellum plasma membrane cytoplasm cell wall

Eukaryotic Cells ¢ Have numerous internal structures ¢ Various types & forms l ¢ Plants, animals, fungi, protists Multicellular organisms

nuclear pore chromatin (DNA) nucleus nucleolus nuclear envelope flagellum rough endoplasmic reticulum cytoplasm intermediate filaments plasma membrane ribosome lysosome microtubules smooth endoplasmic reticulum Golgi complex free ribosome mitochondrion vesicle

microtubules (part of cytoskeleton) mitochondrion chloroplast Golgi complex central vacuole smooth endoplasmic reticulum vesicle cell wall rough endoplasmic reticulum plasma membrane nucleolus nuclear pore chromatin nuclear envelope ribosomes intermediate filaments free ribosome

Eukaryotic cell structure ¢ Nucleus is control center of the cell l 1. Membrane bound (nuclear envelope) l 2. Contains nucleoli; synthesizes ribosomal RNA l 3. DNA in chromosomes (DNA and proteins)

nuclear envelope nucleolus nuclear pores chromatin

nucleus nuclear pores

chromatin chromosome

0. 05 micrometers

Eukaryotic cell structure Organelles Endoplasmic reticulum consists of folded membranes attached to the nucleus Rough ER is site of protein synthesis and protein secretion

rough endoplasmic reticulum ribosomes 0. 5 micrometers smooth endoplasmic reticulum 0. 5 micrometers vesicles

Eukaryotic Cell Structure Organelles (cont. ) Ribosomes assemble amino acid into polypeptide chains • a. Associated with the ER • b. Composed of RNA and proteins

ribosomes rough endoplasmic reticulum 0. 5 micrometers

vesicles smooth endoplasmic reticulum 0. 5 micrometers

Eukaryotic Cell Structure ¢ Organelles (cont. ) l Golgi apparatus are membranous sacs associated with ER • a. Processing and transport of proteins, lipids • b. Synthesis and transport of polysaccharides

vesicles from ER vesicles leaving Golgi complex

Eukaryotic cell structure ¢ Organelles (cont. ) l Lysosomes are Golgi-derived vesicles containing digestive enzymes

vesicles from ER vesicles leaving Golgi complex

Eukaryotic Cells: Organelles Energy sources for cell activities ¢ Mitochondria provide energy for cellular functions (respiration) • a. Membrane bound, numerous • b. Matrix/cristae • c. Have their own DNA and ribosomes; self-replicate

5 micrometers

Eukaryotic Cells: Organelles Energy sources for cell activities • Chloroplasts—function in photosynthesis l 1) Green—contain chlorophyll pigment l 2) Stroma/grana (thylakoid stacks) l 3) Have their own DNA and ribosomes; self-replicate l 4) Up to 100 per cell

Eukaryotic Cells: Organelles ¢ Cytoskeleton l Internal ¢ Surface l l infrastructures extensions of the plasma membrane aid in movement of simple organisms

actin subunits subunit tubulin subunit

Prokaryotes & Eukaryotes ¢ Similarities & differences l Both surrounded by plasma membrane, but very different l Prokaryotes – Archaebacteria and Eubacteria l Eukaryotes – everything else

Evolution of Eukaryotic cell Endosymbiotic Hypothesis Similarities between bacteria, mitochondria and chloroplasts Self-reproducing by binary fission Size of organism and genome Single circular naked DNA Proportion of (G & C) to (A & T) Same sized ribosome Protein synthesis inhibited by antibiotics Enzymes for synthesis of DNA, RNA and protein Electron transport system

Plant & Animal Cells ¢ Similarities l Both constructed from eukaryotic cells l Both contain similar organelles l Both surrounded by cell membrane

Plant & Animal Cells ¢ Differences l Plants have • Cell wall – provides strength & rigidity • Have chloroplasts, photosynthetic l Animals have • Other organelle not found in plants (lysosomes formed from Golgi) • Centrioles, important in cell division

Brief Look at Viruses ¢ Viruses are acellular ¢ Not considered to be living ¢ Cause serious diseases in most organisms