Chapter 7: Cell Structure and Function. 7-1: Life is Cellular The Discovery of the Cell –Robert...
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Transcript of Chapter 7: Cell Structure and Function. 7-1: Life is Cellular The Discovery of the Cell –Robert...
Chapter 7: Chapter 7: Cell Structure Cell Structure and Functionand Function
7-1: Life is Cellular• The Discovery of the Cell
– Robert Hooke coins the term “cell” to describe sections of cork that he sees through his microscope in 1665.
Left: Hooke’s cork cells
Right: cork cells by electron microscope
7-1: Life is Cellular
Around the same time Anton van Leeuwenhoek finds “animacules” in pond water.
7-1: Life is Cellular
This leads to the Cell Theory:1. All living things are composed of cells.
2. Cells are the basic unit of living things.
3. New cells are produced from existing cells.
7-1: Life is Cellular
• Cells come in all shapes and sizes– a typical cell is 5-50 micrometers in diameter– smallest cells (bacteria) are 0.2 micrometers across– Biggest cells (ex: amoeba) can be 1000 micrometers
across – visible with the naked eye Diatom Amoeba
Check out this interactive to get an idea of the scale of cells…
• http://learn.genetics.utah.edu/content/begin/cells/scale/
How big is an e-coli bacteria?
Which is bigger the influenza virus or hepatitis?
7-1: Life is Cellular
Two Broad Categories of Cells
• Prokaryotes and
Eukaryotes– Greek roots
• “pro-” means first or before• “eu-” means true• “-karyon” means kernel
– Both types have cell membranes and DNA– Prokaryotes are much smaller than eukaryotes– Prokaryotes vastly outnumber eukaryotes
White Blood Cell attacking Bacteria
7-1: Life is Cellular
Prokaryotes• No nucleus
(DNA is free-floating in the cytoplasm)
• Bacteria are
prokaryotes
Streptococcus bacteria
7-1: Life is Cellular
Eukaryotes• Contains nucleus
(DNA is contained within the nucleus)
• Single-celled organisms and all multicellular organisms
• Often perform specific functions
White blood cell among red blood cells
7-2: Eukaryotic Cell Structure
• How is a cell like a factory?– Organelles perform specific, repetitive tasks
• “Organelles” means little organs
Organelles inside a cell
7-2: Eukaryotic Cell Structure
Nucleus– Contains DNA (instructions for making
proteins)– Control center for cellular activities– Nuclear anatomy
• Nuclear envelope (porous)• Chromatin (DNA attached to proteins)
– Chromatin becomes chromosomes during cell division
Muscle cells: Nuclei are
stained purple.
7-2: Eukaryotic Cell Structure
Ribosomes– Made of RNA and proteins– Ribosomes make proteins (important!)
• Use amino
acids to make
chains that form
proteins
7-2: Eukaryotic Cell Structure
Endoplasmic Reticulum– Lipid components of cell membrane and
proteins that get exported from the cell are made on the endoplasmic reticulum
– Two types of ER• Smooth ER – synthesis of membrane lipids and
detoxification of drugs• Rough ER
– Called “rough” because of ribosomes on surface– proteins bound for export are chemically modified
7-2: Eukaryotic Cell Structure
Golgi Apparatus (AKA Golgi Body)
– It’s a stack of membranes (like pancakes)– Final touches on proteins after they leave the
endoplasmic reticulum, before they leave the cell– Lysosomes are made by the Golgi apparatus
7-2: Eukaryotic Cell Structure
Protein
Synthesis
7-2: Eukaryotic Cell Structure
Lysosomes– Made by the
Golgi apparatus– Contain
digestive
enzymes –
garbage men
of the cell
7-2: Eukaryotic Cell Structure
Vacuoles– Saclike structures that store materials like
water, salts, proteins, and carbohydrates– Prominent feature of plant cells
7-2: Eukaryotic Cell Structure
Mitochondria– Power HousePower House of the cell
– Energy from glucose is converted into energy that organelles can use
– Inherited from your mother
7-2: Eukaryotic Cell Structure
Chloroplasts– Organelles of photosynthesis (found in plants
and other photosynthetic organisms)– Contain green pigment, called chlorophyll
7-2: Eukaryotic Cell Structure
Organelle DNA– Mitochondria and Chloroplasts have their own DNA!?
American biologist Lynn Margulis has suggested that these organelles are descendants of ancient, independent prokaryotes. The ancestors of modern-day eukaryotes may have developed symbiotic relationships with such prokaryotes millions of years ago.
Mitochondrion Prokaryote
7-2: Eukaryotic Cell Structure
Cytoskeleton– A network of protein filaments that help to
support eukaryotic cells (also help some cells to move)
– Composed primarily
of microfilaments and
microtubules
Microfilaments in red Microtubules in
green