Transcript Chapter 7: Cell Structure and Function

Chapter 7:
Cell Structure
and 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/begi
n/cells/scale/
How big is an e-coli bacteria?
Which is bigger the influenza virus or
hepatitis?
7-1: Life is Cellular
White Blood Cell attacking Bacteria
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
7-1: Life is Cellular
Prokaryotes
• No nucleus
(DNA is freefloating 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
Muscle cells:
Nuclei are
stained purple.
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
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 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
Endosymbiotic
theory
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