Cell Structure & Function
By Back Sroke @SCIE
Nobel Prize & Cell Chemistry Physiology or medicine
2010 Telomeres (DNA)
2009 RNA Viruses & Caner
2008
2007 Stem cell
2006 RNA RNA
2005 Viruses & diseases
2004 Protein
2003 Cell membrane
2002 Programmed cell death
2001 Cell Cycle
2000 Nerve signal
Organisms are made up of cells
Cell Theory• All living things are made up of cells.
• Cells are the basic units of all living things.
• All cells come from pre-existing cells through cell division.
Microscopes
Definition of Cell
A cell is the smallest unit that is capable of performing life
functions.
The size
REVIEW
• List one key point from the cell theory
• What is the definition of a cell?
• What instrument do you use for looking at cells?
Animal cell anatomy
“Typical” Animal Cell
REVIEW• List one main difference between plant
and animal cells
• Do plant and animal cells have organelles?
• What is the function of organelles?
Plant cell anatomy
“Typical” Plant Cell
REVIEW
• What are the main similarities and differences between plant and animal cells?
Cell PartsOrganelles
Surrounding the Cell
Cell Membrane structure
lipid “tail”
phosphate“head”
• Double layers of fat phospholipid bilayer
• Receptor molecule proteins that receive signals
• Carrier proteins Carry ions in and out of the
cell
Cell Membrane structure
• separates cell from outside
• controls materials in and out of the cell O2, CO2, food, H2O, nutrients, waste
• recognizes signals from other cells allows communication between cells
Cell Wall
• Most commonly found in plant cells & bacteria
• Supports & protects cells
• Cellulose cell wall
REVIEW
• Which structure surrounds a cell?
• The functionos of the cell surface membrane?
• The structure of the cell surface membrane?
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Cell Membrane ProteinsCell Membrane Proteins
• Proteins help move large molecules or aid in cell recognition
• Peripheral proteins are attached on the surface (inner or outer)
• Integral proteins are embedded completely through the membrane
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Recognize “self”
GLYCOPROTEINSGLYCOPROTEINS
Glycoproteins have carbohydrate tails to act as markers for cell recognition
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• Lies immediately against the cell wall in plant cells
• Pushes out against the cell wall to maintain cell shape
Cell Membrane in PlantsCell Membrane in PlantsCell membrane
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• Nonliving layer• Found in plants,
fungi, & bacteria• Made of cellulose in
plants• Made of
peptidoglycan in bacteria
• Made of chitin in Fungi
Cell wallCell WallCell Wall
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Cell WallCell Wall• Supports and
protects cell• Found outside of
the cell membrane
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Inside the Cell
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OrganellesOrganelles
• Very small (Microscopic)
• Perform various functions for a cell
• Found in the cytoplasm
• May or may not be membrane-bound
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Animal Cell OrganellesAnimal Cell Organelles
Nucleolus
Nucleus
Nuclear envelope
Ribosome (attached)
Ribosome (free)
Cell Membrane
Rough endoplasmic reticulum
Golgi apparatus
Mitochondrion
Smooth endoplasmicreticulum
Centrioles
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Plant Cell OrganellesPlant Cell Organelles
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• Jelly-like substance enclosed by cell membrane
• Provides a medium for chemical reactions to take place
Cytoplasm of a CellCytoplasm of a Cell
cytoplasm
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• Contains organelles to carry out specific jobs
• Found in ALL cells
More on CytoplasmMore on Cytoplasmcytoplasm
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• Controls the normal activities of the cell
• Contains the DNA in chromosomes
• Bounded by a nuclear envelope (membrane) with pores
• Usually the largest organelle
The Control Organelle - NucleusThe Control Organelle - Nucleus
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• Each cell has fixed number of chromosomes that carry genes
• Genes control cell characteristics
Nucleus
More on the NucleusMore on the Nucleus
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Inside the Nucleus -The genetic material (DNA) is
found
DNA is spread out And appears as
CHROMATINin non-dividing cells
DNA is condensed & wrapped around proteins forming
as CHROMOSOMES in dividing cells
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MitochondrionMitochondrion(plural = mitochondria)(plural = mitochondria)
• “Powerhouse” of the cell• Generate cellular energy
(ATP)• More active cells like
muscle cells have MORE mitochondria
• Both plants & animal cells have mitochondria
• Site of CELLULAR RESPIRATION (burning glucose)
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MITOCHONDRIA
Surrounded by a DOUBLE membrane
(increases surface areafor more chemical Reactions)
Has its own DNA
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Interesting Fact ---Interesting Fact ---
• Mitochondria Come from cytoplasm in the EGG cell during fertilization
Therefore …
• You inherit your
mitochondria from your mother!
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Rod shape
Cell PowerhouseCell Powerhouse
Mitochondrion( mitochondria )
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What do mitochondria do?What do mitochondria do?
Burns glucose to release energy (ATP)
Stores energy as ATP
“ Power plant” of the cell
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Cilia & FlagellaCilia & Flagella
• Cilia are shorter and more numerous on cells
• Flagella are longer and fewer (usually 1-3) on cells
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Cell Movement with Cilia & Cell Movement with Cilia & FlagellaFlagella
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Cilia Moving Away Dust Particles from Cilia Moving Away Dust Particles from the Lungsthe Lungs
Respiratory SystemRespiratory System
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VacuolesVacuoles• Fluid filled sacks for storage• Small or absent in animal cells• Plant cells have a large Central Vacuole• No vacuoles in bacterial cells
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VacuolesVacuoles
• In plants, they store Cell Sap
• Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes
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Contractile VacuoleContractile Vacuole• Found in unicellular
protists like paramecia• Regulate water intake
by pumping out excess (homeostasis)
• Keeps the cell from lysing (bursting)
Contractile vacuole animation
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ChloroplastsChloroplasts
• Found only in producers (organisms containing chlorophyll)
• Use energy from sunlight to make own food (glucose)
• Energy from sun stored in the Chemical Bonds of Sugars
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ChloroplastsChloroplasts• Surrounded by DOUBLE
membrane• Outer membrane smooth• Inner membrane modified
into sacs called Thylakoids• Thylakoids in stacks called
Grana & interconnected• Stroma – gel like material
surrounding thylakoids
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ChloroplastsChloroplasts
• Contains its own DNA
• Contains enzymes & pigments for Photosynthesis
• Never in animal or bacterial cells
• Photosynthesis – food making process
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Cell Size
Question:Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
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Cell Size• When the surface area is no longer great
enough to get rid of all the wastes and to get in enough food and water, then the cell must divide
• Therefore, the cells of an organism are close in size
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Cell SizeQuestion:
Are the cells in an elephant bigger, smaller, or about the same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells than a mouse!
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