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

Organelles

• Specialized structure within a eukaryotic cell that performs a specific function•Have their own membranes•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 ribosomes assembly

begins (they’re made of RNA)• Pores in the nuclear membrane – some molecules in and

out of the nucleus (RNA, 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

Organelles•RIBOSOMES

Organelles•RIBOSOMES

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Organelles•RIBOSOMES

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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

•Golgi ApparatusOrganelles

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

•Review your notes!!!!!!!!!!!!!!!

Homework