Cells and Cell Structures

Cells All living things are made of cells Cells are the basic structural and functional unit of living things New cells are produced from existing cells All cells (prokaryotic and eukaryotic) outer have membranes

Cells Cytoplasm – a thick liquid medium enclosed in the membrane In eukaryotes – “all material” inside the cell and outside the nucleus Mainly composed of water (~80% water), salts and proteins Role – internal substructure, some cell signaling

Cell Membrane Cell membrane – lipid bilayer – stops most things moving in and out

Phospholipid Bilayer

Organelles Function and Location, what do they do and how do they do it: Specialized structure within a eukaryotic cell that performs a specific function Have their own membranes Those with membranes are ONLY in eukaryotic cells

Organelles NUCLEUS Contains MOST of cells DNA (genetic information); coded instructions for making protein Because DNA codes for proteins (enzymes, structures, etc), it ‘controls’ the cell Most of the time DNA is ‘visible’ as chromatin (unwound chromosomes) Nucleolus – dense region where ribosome assembly begins (they’re made of RNA) Pores in the nuclear membrane – some molecules in and out of the nucleus (RNA, small proteins, etc.)

Organelles NUCLEUS

Organelles NUCLEUS Prokaryotes have DNA too, it’s just not in a nucleus

Organelles RIBOSOMES (no membrane) Proteins are ‘translated’ at the ribosome RNA comes from the nucleus Amino acids are brought to the ribosome RNA (copied from DNA) ‘codes’ for amino acids -> proteins So, essential for protein synthesis and no membrane… Also found in prokaryotes NO MEMBRANE!!!!!

Organelles RIBOSOMES

Organelles RIBOSOMES www.mol.biol.ethz.ch 

Organelles RIBOSOMES www.scripps.edu 

Organelles ENDOPLASMIC RETICULUM (ER) Internal membrane system Synthesis site of many different molecules Two types Smooth ER Rough ER

Organelles SMOOTH ER Fat/lipid synthesis (cell membrane parts) Steroid synthesis Carbohydrate metabolism Detoxification

Organelles ROUGH ER Has ribosomes on it – giving it a ‘rough’ look Protein synthesis – mostly for proteins leaving the cell Enzymes for lysosomes Membrane proteins

Organelles Golgi Apparatus (or Body) Stacked membranes in the cytoplasm Packages proteins (from rough ER) to be released outside the cell

Organelles Golgi Apparatus

Organelles Golgi Apparatus (or Body) Stacked membranes in the cytoplasm Packages proteins (from rough ER) to be released outside the cell Why put membrane around them to transport? Packages other molecules for transport as well

Organelles Mitochondrion (singular) Uses energy (electrons and protons!) from molecules to make an ‘energetic molecule’ for your cells = ATP CONVERTS energy into form usable by cell Has TWO membranes – inner and outer

Organelles Mitochondrion

Organelles Mitochondrion (singular) Inherited from your mother (from the egg) Mitochondria from sperm cell are left behind with the flagellum at fertilization They have their OWN DNA!!!! We’ll spend a lot more time on these in the future

Organelles Chloroplast Capture energy from sunlight and use it to make sugars Uses solar energy to take electrons and protons from water!!! Energy from these electrons and protons are then used to ‘make’ the sugars Chlorophyll inside ‘captures’ solar energy Two membranes again

Organelles Chloroplast

Organelles Chloroplast And their OWN DNA!!!! Yes, we’ll be spending a lot more time on them in the future

Homework Venn Diagram – mitochondrion and chloroplast