A Tour of the Cell AP Biology Crosby

A Tour of the Cell AP Biology Crosby High School

Microscopes and Early Cell Descriptions Robert Hooke – Entertaining the Royal Society – “Cells” in Cork slices Anton van Leeuwenhoek – Observed animalcules in plaque – First to describe bacteria

Prokaryotic and Eukaryotic Cytosol Chromosomes Ribosomes Plasma membranes

Eukaryotic Cells Eu (true) karyon (kernel) Contain a nucleus – Surrounded by a nuclear envelope Cytoplasm – Entire area between the nucleus and cell membrane Membrane bound organelles – Specialized functions

Prokaryotic Cells Pro (before) karyon (kernel) Contain a nucleoid – Region of the cell concentrated with DNA

Plant Cell vs. Animal Cell

Nucleus Contains MOST of the genetic material Nuclear Envelope – Double membrane each consisting of phospholipid bilayers – Porous membrane for import and export DNA organized into chromatin – Condenses to chromosomes before cell reproduction 46 chromosomes in human somatic cells 23 chromosomes in human gametes

Nucleus (cont. ) Nucleolus – Produces r. RNA – Ribosomal subunits exit through pores to form Ribosomes Protein Synthesis – Creates m. RNA – Used to create primary structure

Ribosomes Carry out Protein Synthesis – DNA –transcription PROTEIN RNA –translation Made of r. RNA and Proteins Rate of Protein Synthesis related to Number of Ribosomes

Types of Ribosomes Free Ribosomes – Create Proteins in Cytosol – Sugar Breakdown Bound Ribosomes – Attached to other organelles Nuclear envelope ER – Proteins made Membrane insertion Export from cell Interchangeable

Endomembrane System

Endoplasmic Reticulum (The factory of the cell) Manufactures membranes Performs Biosynthetic functions Membranous labyrinth of tubules and cisternae Continuous with nuclear envelope Smooth and Rough Endomembrane System

Smooth ER Produces lipids Contains enzymes that detoxify drugs and poison – Adds alcohol – Inducing proliferation increases tolerance Muscle cells – Pumps Ca 2+ into cisternal space – Nerve impulse pulls calcium back out

Rough ER Polypeptides grow and enter cisternal space Safely fold to native structure Forms glycoproteins Proteins enclosed in vesicles before departure Makes phospholipids for cell and self

Golgi Apparatus (The shipping yard of the cell) Finishes, sorts, and ships cell products Vesicles transport between the golgi and other structures Two distinct faces – Cis: located near the ER (receiving dock) – Trans: located away from the ER (shipping dock) Vesicles pinch off of this end for transport Endomembrane System

Golgi Apparatus (cont. ) Created from Cis to Trans Produces Polysaccharides Products tagged before departure

Lysosomes Membrane bound sacs digest macromolecules – Enzymes function @ p. H 5 – Ruptured lysosomes Amoebas and Macrophages – Phagocytosis (“phagein” (to eat); “kytos” (vessel)) – Vacuole fuses with lysosome Autophagy: Lysosomes as recycling centers Apoptosis: programmed cell death

Vacuoles (cell maintenance) Food vacuoles Contractile vacuoles (freshwater protists) Central Vacuole (plants) – Tonoplast – Has many uses Disposal Pigmentation Toxins

Mitochondria Cellular Respiration 2 Bilayers – Outer: smooth – Inner Cristae Intermembrane space Mitochondrial matrix – Enzymes – Mitochondrial DNA Membrane Proteins – Cellular respiration

Chloroplast Part of Plastid family – Amyloplasts: starch – Chromoplasts: yellow & orange – Chloroplasts: green Structure – – – Thylakoids Granum Stroma DNA, ribosomes and enzymes

Peroxisomes Transfer H to O creating H 2 O 2 – O breaks fatty acids into smaller molecules – Detoxification – H 2 O 2 is turned into water Grow from proteins and lipids from cytosol Glyoxisomes – Fatty acids converted to sugar (seeds)

Cytoskeleton Structural support – Anchors organelles – Often reassembled Cell motility – ATP powered motor molecules Regulation

Three types of fibers Microtubules – Shape and support – Tracks – Centrosomes and centrioles Centrosomes: keep form from compressing Centrioles: – Separates – Act as basal bodies

Microtubules (cont. ) Cilia: move the cell perpendicular Flagella: move the cell parallel Similarities – “ 9+2” pattern – Anchored by basal body – Dynein Responsible for “walking” Proteins restrict movement to create bending

Microfilaments Also called Actin Muscle cells – Actin and myosin “walk” along each other Amoeboids – Extend Pseudopodia and flow to move Intermediate Filaments Made of Keratin

Cell Membrane