cp bio : chapter 7 cell structure and function
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CP BIO : Chapter 7 Cell Structure and Function. The cell is the basic unit of life. 1. Discovery of the Cell. Robert Hooke 1660s cork “cells” Anton von Leeuwenhoek 1660s first high-mag microscope living cells, bacteria Pond water, blood, saliva. All living things made of cells. - PowerPoint PPT PresentationTRANSCRIPT
CP BIO: Chapter 7 Cell Structure and Function
The cell is the basic unit of life
1
Discovery of the Cell• Robert Hooke 1660s
– cork “cells”
• Anton von Leeuwenhoek 1660s– first high-mag microscope– living cells, bacteria– Pond water, blood, saliva
All living things made of cells
• Matthias Schleiden 1830s– all plants made of cells
• Theodore Schwann 1830s – all animals made of cells
• Rudolf Virchow 1850s– new cells come from cell division
3
The Cell Theory
1. All organisms are made of one or more cells2. The cell is the basic unit of life. Cells that
form part of a larger organism still do their own life processes.
3. All cells come from pre-existing cells
4
Why are all cells small?
Cells vary in size and shape
• Must contain raw materials and molecules needed by cell
• Must have fast exchange with environmentSurface area must be large compared to volume
5
size increases (1mm2mm) 2X (14) 4X
area increases (24/6) 4X (96/6) 16X
volume increases (8/1) 8X (64/1) 64X
Cells have large Surface-to-Volume Ratio
6
Two basic kinds of cells Prokaryotic Eukaryoticsmall and simple larger and more
complexno nucleus nucleusbacteria all other organisms
Both have: DNA & complex chemicals, cell membrane, cytoplasm, ribosomes
Two kinds of cells
Bacteria (purple) in animal cell (pink)
8
Prokaryotes “before nucleus”
9
All prokaryotes have1. Nucleoid
• Region containing DNA, one chromosome2. Cell (plasma) membrane
• Encloses cytoplasm• Controls what enters and leaves cell
3. Cell wall• Outside membrane• Cell shape and protection
10
SOME prokaryotes have
4. Capsule – protective layer • Slimy or sticky coating, outside cell wall
5. Pili – extensions of cytoplasm• to attach to other cells, pass signals
6. Prokaryotic flagella – for movement7. Plasmids – small rings of DNA
• have special genes
11
Some prokaryotic cells
Common shapes of bacteria
12
Eukaryotic Cells “true nucleus”
Eukaryotes have membrane compartments– Larger than prokaryotes (10-100 m)– Many organelles – tiny “organs”, with specific
functions– Most organelles are enclosed by a membrane
• Keeps chemistry inside organelle separate from rest of cell
13
7.2 Cell StructureThe cell is like a city – every part has a job to do. Together these parts keep the cell alive.
Cytoplasm
• Watery solution outside nucleus
• Has many dissolved substances for metabolism
• Site for chemical reactions• Contains organelles, each
has a function
15
Nucleus- control center of cell
• Has most of the DNA • Chromosomes – structures
containing DNA• Chromatin – loose, thread-
like form of chromosomes when cell is not dividing
• Nucleolus – makes ribosomes
16
Nuclear Envelope
• Membrane surrounding nucleus• Many pores for molecules to pass through• Selectively permeable – controls what moves
in and out of nucleus
17
Organelles that Build Proteins
Ribosomes• Makes proteins, uses instructions in DNA• Made of RNA and protein• Made in nucleolus, move to cytoplasm and
rough ER
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Endoplasmic Reticulum- membrane channels throughout cell- make and transport materials- large surface area for reactions
Rough ER - has ribosomes - makes and modifies proteins
Smooth ER• No ribosomes on membrane • Makes and transports lipids• Other functions in special tissues
20
Golgi Apparatus
• Layers of membrane sacs• Receives proteins made in ER• Sorts and packages proteins
into tiny vesicles• Final products may be used by
cell (ex. lysosome) or exported from cell
21
LysosomesMembrane sacs of digestive enzymes1. Break down wastes and worn-out cell parts2. Recycle molecules the cell can use3. In one-celled, join to food vacuoles to digest food 4. In development, remove tissue no longer needed (ex. tadpole tail)5. In defense, white blood cells digest bacteria6. In Cell death – when cell is damaged beyond repair
Organelles that capture and release energy
Mitochondria“Powerhouse of the cell” – site for cell respiration• Releases chemical energy from food and
changes into energy cell can use ATP• ATP – energy molecule in all organisms
22
Plastids – in plants Chloroplasts• Site for photosynthesis: capture sun energy and
change it into chemical energy of food• Layered membranes inside contain green pigment
chlorophyll
23
Leukoplasts and Chromoplasts
Leukoplasts store starch
Chromoplasts store other pigments -flowers, fruits, seeds
24In red pepper
In potato
Mitochondria and Chloroplasts are different from other organelles
1. double-layered membrane organelles - inner membrane deeply folded/layered - large surface area for fast chemical processes
2. have their own DNA and ribosomes- can self-replicate as needed
- make their own enzymes for reactions
Organelles that store and clean up
Food vacuole in paramecium
Plant Vacuoles
Stores water and substances needed for photosynthesis
Also has enzymes to recycle molecules
27
Contractile Vacuole
• In some one-celled organisms that live in fresh water
• Water enters cell from environment
• Vacuole pumps out excess water
• Keeps homeostasis
28
30
Lysosomes are stained in this slide
The Cytoskeleton
• Protein framework inside cell• Attach to cell membrane to
keep cell shape• Anchor organelles• Transport materials inside
cellTwo kinds: microfilaments and microtubules
31
Microfilaments
• Flexible, elastic threads• Support cell and help cells move
– Move substances around inside cell– Cytoplasmic streaming– May form pseudopods
Cytoplasmic streaming lets
amoeba eat by encircling food 32
Microtubules
• Hollow rigid tubes keep cell shape• Tracks for moving molecules in cell• Also found in cilia, flagella (for movement) and in
centrioles and spindle fibers (for cell division)
33
Cytoskeleton and Cell Wall
Cilia and FlagellaExtensions on cell surface
• Cilia – short, many, like “oars”– Ex. line air passages in our body
- cover Paramecium
• Flagella – longer, one or a few, move like a “whip”– Ex. Human sperm, euglena
35
Centrioles and Spindle Fibers
• Help in cell division• Centrioles (only in animal cells)
– Organize spindle fibers• Spindle fibers (in all eukaryotic cells)
• Organize and separate chromosomes when cell divides
36
Cell BoundariesKeep cell contents separated from surroundings
Cell (plasma) membrane – in ALL CELLS• Selectively permeable• controls which substances move in or out of
cell• Maintains homeostasis
37
The Cell Membrane
Double layer of phospholipids and proteins
The Cell Wall• In many organisms, but NOT animals• Outside cell membrane• For shape, support, protection• Some substances can pass through• In plants – mostly cellulose• Also in fungi, most bacteria, some protists
Cellulose fibers in cell wall
37
Cell Junctions• Connects cells to form tissues• Cells can communicate and share materials
Gap junction anchoring junction tight junction
How do plant and animal cells differ? Plant cells also have:
1. rigid cell wall, contains cellulose 2. chloroplasts – do photosynthesis
3. large central vacuole – stores water and molecules for photosynthesis
Animal cells have: 1. centrioles – for cell division
2. lysosomes – break down wastes3. some have flagella or cilia
42
Endosymbiosis TheoryTheory for how eukaryotic cell evolved
1. Prokaryotes are different sizes2. Larger prokaryotes ate smaller ones3. Some were not digested, but became part of cell4. Might have survival advantage
– ex. make its own food; use energy efficiently
Endosymbiosis Theory
Evidence to support theory
Chloroplasts and mitochondriaa) have double membranesb) Have their own DNA and ribosomesc) Can self-replicate
May have once been separate organisms