Biology 1- Chapter 7 NotesPrentice Hall (pg. 168-193)

• 7–1 Life Is CellularA. The Discovery of the Cell

1. Early Microscopes2. The Cell Theory

B. Exploring the CellC. Prokaryotes and Eukaryotes

1. Prokaryotes2. Eukaryotes

• 7–2 Eukaryotic Cell Structure A. Comparing the Cell to a Factory

B. Nucleus C. Ribosomes D. Endoplasmic Reticulum E. Golgi Apparatus

F. Lysosomes G. Vacuoles H. Mitochondria and Chloroplasts

1. Mitochondria 2. Chloroplasts

3. Organelle DNA I. Cytoskeleton

• 7–3 Cell BoundariesA. Cell MembraneB. Cell WallsC. Diffusion Through Cell Boundaries

1. Measuring Concentration2. Diffusion

D. Osmosis1. How Osmosis Works2. Osmotic Pressure

E. Facilitated DiffusionF. Active Transport

1. Molecular Transport2. Endocytosis and Exocytosis

• 7–4 The Diversity of Cellular Life

A. Unicellular OrganismsB. Multicellular Organisms

1. Specialized Animal Cells2. Specialized Plant Cells

C. Levels of Organization1. Tissues2. Organs3. Organ Systems

7.1: The History of the Cell Theory

• Before microscopes were invented, people believed that diseases were caused by curses and supernatural spirits.

• As scientists began using microscopes, they quickly realized they were entering a new world–one of microorganisms.

• Microscopes enabled scientists to view and study cells, the basic units of living organisms.

Development of Light Microscopes

• The first person to record looking at water under a microscope was Anton van Leeuwenhoek.

• The microscope van Leeuwenhoek used is considered a simple light microscope because it contained one lens and used natural light to view objects.

• Compound light microscopes use a series of lenses to magnify objects in steps.

• These microscopes can magnify objects up to 1500 times.

The Cell Theory• Robert Hooke was an

English scientist who lived at the same time as van Leeuwenhoek.

• Hooke used a compound light microscope to study cork, the dead cells of oak bark.

• He thought the structures he observed resembled the one room “cells”

• Hooke is credited with giving cells their name

• Cells are the basic building blocks of all living things.

The cell theory is made up of three main ideas:

1. All organisms are composed of one or more cells.2. The cell is the basic unit of structure and function of

organisms.3. All cells come from preexisting cells.

Three Scientists contributed to the Cell Theory: • 1838- Schleiden: plants are made of cells• 1839- Schwann: animals are made of cells• 1855- Virchow: New cells are produced from the

division of old cells

Development of Electron Microscopes

• The electron microscope was invented in the 1940s.

• This microscope uses a beam of electrons to magnify structures up to 500,000 times their actual size.

There are two basic types of electron microscopes.

• The scanning electron microscope scans the surface of cells to learn their three dimensional shape.

• The transmission electron microscope allows scientists to study the structures contained within a cell.

Scanning Probe Microscope

• Discovered in the 1990’s

• Produces images by tracing the surfaces of samples with a fine probe

• Can observe single atoms in the air or in solution SEM Picture

of NeuronCondensed DNA by

Scanning probe

Two Basic Cell Types

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Prokaryotic and Eukaryotic Cells

Prokaryotic Cells• Cells that do not

contain internal membrane-bound structures and do not have a nucleus are called prokaryotic cells.

• Unicellular organisms such as bacteria are very simple.

• They still carry out all of life’s activities such as respiration, cell reproduction, growth, etc.

Prokaryotic Cell

Eukaryotic Cells• Cells containing

membrane-bound structures and a nucleus are called eukaryotic cells.

• Most of the multi-cellular plants and animals are made up of cells that are very specialized and diverse in their structures and functions

Eukaryotic Cell

7.2 Eukaryotic Cell StructureOrganelles

• The membrane-bound structures within eukaryotic cells are called organelles.

• Each “little organ” has a specific function that contributes to cell survival.

• Separation of organelles into distinct compartments benefits the eukaryotic cells.

• Lysosomes• Nucleus

• Plasma Membrane• Endoplasmic Reticulum

• Mitochondrion

Biologists divide the cell into two major parts

• The nucleus is the central membrane-bound organelle that manages cellular functions.

• Everything between the cell membrane and the nucleus is called the cytoplasm.

Nucleus- Nuclear envelope – double layered membrane surrounding

nucleus; contains small pores- Nuclear pores- allow transport of materials in and out of nucleus- Chromatin-granular material visible within the nucleus; consists of

DNA tightly coiled around proteins - Chromosomes – threadlike

structure within the nucleus containing the genetic information that is passed from one generation of cells to the next (chromosomes are formed when chromatin condenses during cell division)

- Nucleolus – dense material in nucleus; makes ribosomes which make proteins

Chromatin Nucleolus

Nuclear Envelope

Nuclear Pore

Ribosomes• Ribosomes are made in the

nucleolus.• They travel in and out of the

nucleus through the nuclear pores.

Ribosomes

• Ribosomes are small particles within the cell on which proteins are assembled; made of RNA and protein

• They can be free (in the cytoplasm)

• They are also attached to the rough endoplasm reticulum

Endoplasmic reticulum• The endoplasmic reticulum

(ER) is responsible for assembly, transport, and storage of molecules within cell.

• There are two types

• Rough ER- contains ribosomes and makes proteins

• Smooth ER- lacks ribosomes; has enzymes that make membrane lipids and detoxifies drugs

• Liver cells contain many smooth ER for detoxification

Golgi Apparatus• Stacks of membranes

in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum

• The Golgi apparatus is like a customization shop where finishing touches are added to proteins.

Lysosomes• Lysosomes are organelles that contain

digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

• The lysosomes are the clean-up crew of the cell

• Tay-Sachs disease is caused by excess lipid accumulation on the brain. The cause of this disease has been traced to lysosomes that failed to function properly

Vacuoles• Vacuoles are membrane-bound spaces used for

temporary storage of materials (such as water, salts, proteins, and carbohydrates)

• Notice the difference between vacuoles in plant and animal cells.

VacuoleAnimalCell

PlantCell

• Paramecium have a contractile vacuole that pumps excess water out of the cell, which aids with homeostasis

Mitochondria• Mitochondria are

membrane-bound organelles in plant and animal cells that transform energy for the cell.

• A mitochondria, like the endoplasmic reticulum, has a highly folded inner membrane.

• The folds increase the surface area of the mitochondrion in order to make more energy (ATP)

• Cellular Respiration takes place in the mitochondria of cells

• Cellular respiration is the process that converts chemical energy stored in food into ATP energy for cells to use.

• Muscles cells (needed for movement) contain a large number of mitochondria for energy production

Chloroplasts

• Chloroplasts are found in cells of plants and some other organisms

• Chloroplasts are organelles that capture light energy and produce food to store for a later time.

• Photosynthesis takes place in the chloroplasts

• Chloroplasts contain green pigment called chlorophyll.

• Chlorophyll traps light energy and gives leaves and stems their green color.

• Chloroplasts acts like a solar power plant

Organelle DNA• Lynn Margulis - described mitochondria and chloroplasts as

free-living aerobic prokaryotes which developed a partnership with host cell; endosymbiosis hypothesis

• chloroplasts and mitochondria have their own circular DNA & ribosomes, make their own proteins, reproduce on their own

Cytoskeleton• Cells have a support structure called the

cytoskeleton within the cytoplasm. • It is a network of proteins that help maintain

cellular shape and movement• The cytoskeleton is composed of microtubules and

microfilaments.

• Microtubules are thin, hollow cylinders made of protein that maintain cell shape

• Microfilaments are thin solid protein fibers that help cells move (amoeba)

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

Centrioles• Made of microtubules and cytoskeleton• one of two tiny structures located in the cytoplasm of

animal cells near the nuclear envelope • help to organize cell division (helps cells split into two)• only found in animal cells

Cilia and Flagella• Some cell surfaces have cilia and flagella,

which are structures aid in locomotion or feeding.

• Made of microtubules from the cytoskeleton

• Cilia and flagella can be distinguished by their structure and by the nature of their action.

• Cilia are short, numerous, hair-like projections that move in a wavelike motion.

• Flagella are long projections that move in a whip-like motion.

• Flagella and cilia are the major means of locomotion in unicellular organisms.

Cilia

Flagella

Microscope Lab

• Purpose :To compare the basic structures and shape of plant and animals cells by looking at onion (epidermal) cells and cheek (epithelial) cells– epidermal cells- cells that make up the protective outer

covering of plants; tissue that covers the human body– epithelial cells- cells that make up tissues that cover bodies

or organs• To review basic microscope parts and lab techniques like

staining cells and preparing a wet mount for microscope slides

Plant Cells Animal Cells• Shape Rectangular Circular• Components Cell wall Cell Membrane

Cell Membrane NucleusNucleus

Plant cells have structures not found in animal cells

• Cell wall - help give plants shape, support and protection

• Chloroplast-site of photosynthesis

• Large central vacuole - contains water which helps keep plant from wilting; when the vacuole is full it presses against the cell wall to give the plants rigidity (turgid pressure)

Animal cells have structures not found in plant cells

• Cytoskeleton- animal cells use the cytoskeleton to help with support and aid in movement

• Centrioles-aid in cell division

Differences between Plant/Animal Cells

Animal Cells Plant Cells

Centrioles

Cell membraneRibosomes

NucleusEndoplasmic reticulum

Golgi apparatusLysosomes

VacuolesMitochondriaCytoskeleton

Cell WallChloroplasts

Animal Cell

Animal Cell

Centrioles

NucleolusNucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrion

CellMembrane

Ribosome(free)

Ribosome(attached)

Plant Cell

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

7.3: Cellular Boundaries• The cell membrane acts as a semi-permeable membrane.

• The cell wall is a fairly rigid structure located outside the plasma membrane that provides additional support and protection.

• It is present in plants, algae, fungi, and many prokaryotes. • Allows water oxygen, carbon dioxide to pass through easily• Plant cell walls are made of cellulose (fiber)

Cell Membrane• All cells are surrounded by the cell membrane• It regulates what enters and leaves the cell and

provides protection and support– It protects against viral and bacterial invaders

• It consists of two layers called the lipid bilayer.• The cell membrane is also called the plasma membrane

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

The Structure of the Cell Membrane• Lipids (lipid bilayer) • Proteins embedded in bilayer

– Some proteins form channels or pumps to move material across the membrane

• Carbohydrates attached to proteins– These act as signals or identification cards, allowing the cells to

recognize each other• Because it allows different components to move through it, it is also

called the “fluid mosaic model”

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

The Plasma Membrane• All living cells must maintain a

balance regardless of internal and external conditions. Survival depends on the cell’s ability to maintain the proper conditions within itself.

Why cells must control materials

• The plasma membrane is the boundary between the cell and its environment.

It is the plasma membrane’s job to: • allow a steady supply of glucose, amino acids, and lipids to

come into the cell no matter what the external conditions are.• remove excess amounts of these nutrients when levels get

so high that they are harmful.• allow waste and other products to leave the cell.

Cell membrane• This process of

maintaining the cell’s environment is called homeostasis.

• Semi- (selectively) permeability is a process used to maintain homeostasis in which the plasma membrane allows some molecules into the cell while keeping others out.

Water

Plasma Membrane

Diffusion• The process by which molecules tend to move from an area where

they are more concentrated to an area where they are less concentrated.

• Molecules move through cell boundaries• Concentration- the amount of solute in a given amount of solution• Equilibrium- when the concentration of a solute is the same

throughout the solution • Does not require energy; moves down the concentration gradient (HL)• Moves oxygen, carbon dioxide and water

Osmosis• diffusion of water through a selectively permeable

membrane

Water will keep moving until equilibrium is reached

Hypertonic Solution

• concentration of solutes in solution is higher than the concentration of solutes inside the cell

• causes water to diffuse out of the cell; may cause cell to shrivel and shrink; disrupts metabolism and may kill cell

Hypotonic Solution

• concentration of solutes is lower than the concentration inside the cell

• causes water to diffuse into the cell

• animal cells may burst in a hypotonic solution

• plant (and many bacteria) cells do not burst because they are surrounded by a rigid cell wall

Isotonic Solution

• the concentration of solutes equals the concentration of solutes inside the cell

• does not result in the net diffusion of water into or out of the cell

• kidneys and skin help to maintain isotonic conditions in your body

The Effects of Osmosis on Cells

Facilitated Diffusion• movement of specific

molecules across cell membranes through protein channels

• passive - does not require an input of energy

• always moves particles down a concentration gradient (HL)

• because these molecules re polar they must travel through channels in transport proteins;ex: glucose

HighConcentration

LowConcentration

CellMembrane

Glucosemolecules

Proteinchannel

Active Transport • energy-requiring process that

moves material across a cell membrane against a concentration difference

• requires energy from ATP molecules

• can move particles up a concentration gradient (from low to high)

• requires carrier proteins to “pump” particles across membrane

• ex: Na-K pumps in nerve cells, movement of nutrients into plant roots

Molecule tobe carried

Moleculebeing carried

Energy

Bulk transport - large molecules, food, and other substances are packaged in membrane-bound sacs and moved across the membrane

• The graph to the right shows the relative size of molecules that move in and out of the cell

• Requires energy• Endocytosis

– Phagocytosis– Pinocytosis

• Excoytosis

Endocytosis• process by which a cell takes

material into the cell by infolding of the cell membrane

Two Types• Phagocytosis (cell eating)-

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell  

• Pinocytosis (cell drinking)-process by which a cell takes in a liquid from the surrounding environment

Amoeba ingesting food

Exocytosis• wastes and cell

products leave the cell by fusing with membrane

• products packaged by Golgi apparatus and excreted from cell

• Removal of water by the contractile vacuole of paramecium.

7.4- Diversity of Cellular LifeUnicellular Organisms

• Sometimes single cells are the organism

• Grow, respond to the environment, transform energy, and reproduce

Multicellular Organisms• Made up of many cells• Very diverse• Depend on communication

and cooperation between specialized cells

Cell specialization• Cells throughout an

organism can develop in different ways to perform different tasks

Yeast Volvox Bacterium

Cell Specialization Animal cells

• Red Blood Cells- carries oxygen; small and round to fit through vessels

• Pancreatic Cells- produce enzymes to break down food; contains many ribosomes and rough ER to aid in this process

• Muscle Cells- long and threadlike to aid in movement; contain many mitochondria for energy production

Plant Cells• Guard cells- in the pores of leaves; aids in

water exchange

Cell Shape is Related to Function

Levels of Organization

• Many multicellular organisms have structures called organs that have a specific function and work with other organs.

• Working together, these organs carry out the life processes of the entire organism.

• Multicellular organisms contains cells, tissues, organs and organ systems

Muscle cell Smooth muscle tissue Stomach Digestive system