+ Life on a Cellular Level Mrs. Geist Biology Fall 2010-2011.

+

Life on a Cellular LevelMrs. Geist

Biology

Fall 2010-2011

+Warm-Up 09/08/10

What is a cell?

Does a smaller organism have smaller or fewer cells? Why?

Does a larger organism have larger or a greater number of cells? Why?

+Standards/Essential Questions SCOS 2.02 Investigate and describe the

structure and function of cells including: cell organelles, cell specialization, communication among cells within an organism.

Essential question(s): - What are the three parts of the cell theory?

What is the relationship between surface area and volume?

Why are there limits on cell size?

Distinguish between prokaryotes and eukaryotes.

+Cell Size

Cell size is limited

Smaller cells are more efficient than larger cells.

Surface area-to-volume ratio decreases as a cell grows larger in size Harder for larger cells to pass materials in

and out of the cell membrane and throughout the cell

+Surface Area-to-Volume Ratio

To simplify things, we will consider cells to be cuboidal for this exercise.

Surface area = length x width x 6 sides

Volume = length x width x height

Ratio = surface area/volume

Complete the data table


Cell Dimensions (cm)

Surface Area (cm2)

Volume (cm3)

SA/V Ratio

1 1 x 1 x 1

2 2 x 2 x 2

3 4 x 4 x 4

4 8 x 8 x 8


Cell Dimensions (cm)

Surface Area (cm2)

Volume (cm3)

SA/V Ratio

1 1 x 1 x 1 = 1 x 1 x 6= 6

= 1 x 1 x 1 = 1

= 6/1 = 6 = 6:1

2 2 x 2 x 2 = 2 x 2 x 6 = 24

= 2 x 2 x 2 = 8

= 24/8 = 3 = 3:1

3 4 x 4 x 4 = 4 x 4 x 6 = 96

= 4 x 4 x 4 = 64

= 96/64 = 1.5 = 3:2

4 8 x 8 x 8 = 8 x 8 x 6 = 384

= 8 x 8 x 8 = 512

= 384/512 = 0.75 = 3:4

+Why study cells?Cell biology aids in understanding human diseases and the design of therapeutics to treat these diseases.

Duchene muscular dystrophy

Cystic fibrosis Sickle cell anemia

+Multicellular organisms are made up of many different cell types that each carry out a particular function.

+The Discovery of the Cell Cells are not visible to the naked eye.

Early Microscopes In 1665, Robert Hooke used an

early compound microscope to look at a thin slice of cork, a plant material.

Cork looked like thousands of tiny, empty chambers.

Hooke called these chambers “cells.”

The cell is the basic unit of life.Hooke’s Drawing of Cork Cells

+The Discovery of the Cell

At the same time, Anton van Leeuwenhoek used a single-lens microscope to observe pond water and other things.

The microscope revealed a world of tiny living organisms.

+The History of the Cell

1838- Matthias Schleiden concluded that all plants were made of cells.

1839- Theodor Schwann stated that all animals were made of cells.

1855- Rudolph Virchow concluded that new cells were created only from division of existing cells.

These discoveries led to the cell theory.

+The Cell Theory

1. All living things are composed of cells.

2. Cells are the basic units of structure and function in living things.

3. New cells are produced from existing cells.

+Cells

Cells come in a variety of shapes and sizes.

All cells:are surrounded by a barrier called a

cell membrane.at some point contain DNA.

+The Nucleus

Cells are classified into two categories, depending on whether they contain a nucleus. Eukaryotes are cells that contain nuclei. Prokaryotes are cells that do not contain nuclei.

Nucleus- large membrane-enclosed structure that contains the cell's genetic material (in the form of DNA).

The nucleus controls many of the cell's activities.

+Nucleus

+Prokaryotes

Prokaryotic cells have genetic material that is not contained in a nucleus.

do not have membrane-bound organelles.

generally smaller and simpler than eukaryotic cells.

Ex: bacteria

+Eukaryotes

Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.

generally larger and more complex than prokaryotic cells.

generally contain dozens of structures and internal membranes.

Many eukaryotic cells are highly specialized.

Ex: Plants, animals, fungi, and protists

+

Rapid Review09/08/2010

To be completed in class work section of your binder.

Copyright Pearson Prentice Hall

+

The cell theory states that new cells are produced from nonliving material. existing cells. cytoplasm. animals.


+

The person who first used the term cell wasa. Matthias Schleiden.b. Lynn Margulis.c. Anton van Leeuwenhoek.d. Robert Hooke.

+Homework

Define the following terms in your own words: (1) organelle, (2) nucleus, (3) plasma membrane, (4) selective permeability, (5) phospholipid, (6) fluid mosaic model, and (7) transport protein.

Fold your paper in half lengthwise. Terms go on the left-hand side. Definitions go on the right-hand side.

Due tomorrow, Thursday 09/09/10.

+Warm-up 09/09/10

Describe why oil and water do not mix.

What kinds of substances might need to enter a cell?

What kinds of substances might need to leave a cell?

+Eukaryotic Cell Structures

Structures within a eukaryotic cell that perform important cellular functions are known as organelles.

Cell biologists divide the eukaryotic cell into two major parts: Nucleus

The nucleus is the control center of the cell. Contains nearly all the cell's DNA, which is the coded instructions

for making proteins and other important molecules.

Cytoplasm The cytoplasm is the portion of the cell outside the nucleus.


+Plant Cell

Nuclear envelope

Ribosome (free)

Ribosome (attached)

Mitochondrion

Golgi apparatus

Vacuole

NucleolusNucleusSmooth

endoplasmic reticulum

Rough endoplasmic reticulum

Cell wall

Cell membrane

Chloroplast


+Animal Cell

Smooth endoplasmic reticulum

Ribosome (free)

Ribosome (attached)

Golgi apparatus

Mitochondrion

Rough endoplasmic reticulum

Cell membrane

Nucleus

Nuclear envelope

Nucleolus

Centrioles


+The Structure of the Nucleus

Nucleolus Nuclear envelope

Nuclear pores

Chromatin


+The Structure of the Nucleus

The nucleus is surrounded by a nuclear envelope composed of two membranes.

The envelope is dotted with nuclear pores

Nuclear pores allow material to move in and out of the nucleus.

Nuclear envelope

Nuclear pores


+Chromatin

The granular material in the nucleus is called chromatin.

Chromatin consists of DNA bound to protein.

Chromatin


+Chromosomes

When a cell divides, chromatin condenses to form chromosomes.

Chromosomes contain the genetic information that is passed from one generation of cells to the next.


+Nucleolus

Most nuclei also contain a nucleolus.

The nucleolus is where the assembly of ribosomes begins.

Nucleolus

+Ribosomes

One of the most important jobs carried out in the cell is making proteins.

Proteins are assembled on ribosomes.

Ribosomes are small particles of RNA and protein found throughout the cytoplasm.


+Ribosomes

Ribosomes produce proteins by following coded instructions that come from the nucleus.

Cells that are active in protein synthesis are often packed with ribosomes.

+Endoplasmic ReticulumEukaryotic cells contain an internal membrane system called the endoplasmic reticulum, or ER.

The endoplasmic reticulum is where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell.

2 types of Endoplasmic Reticulum

1. Smooth ER

2. Rough ER


Ribosomes

Endoplasmic Reticulum


+2 Types of Endoplasmic Reticulum1. Rough Endoplasmic Reticulum

Involved in protein synthesis Ribosomes are found on the surface of the Rough (ER) Abundant in cells that produce large amounts of protein

for export. Proteins produced in the Rough ER move into the Golgi

apparatus.

2. Smooth Endoplasmic Reticulum Does not have ribosomes on its surface. Contains enzymes that perform specialized tasks

Synthesis of membrane lipidsdetoxification of drugs.


+Golgi Apparatus

The Golgi apparatus modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or secretion outside the cell.

From the Golgi apparatus, proteins are then “shipped” to their final destinations throughout the cell or outside of the cell.


+Golgi ApparatusThe Golgi apparatus modifies, sorts, and packages proteins.

Notice the stacklike membranes that make up the Golgi apparatus.


+Lysosomes

Lysosomes are small organelles filled with enzymes.

Lysosomes break down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell.

Lysosomes also break down organelles that have outlived their usefulness.


+Vacuoles

Some cells contain saclike structures called vacuoles that store materials such as water, salts, proteins, and carbohydrates.

In many plant cells there is a single, large central vacuole filled with liquid.

The pressure of the central vacuole allows plants to support heavy structures such as leaves and flowers.

Vacuole


+Vacuoles

Vacuoles are also found in some unicellular organisms and in some animals.

The paramecium contains a contractile vacuole that pumps excess water out of the cell.

Contractile vacuole


+Mitochondria Nearly all eukaryotic cells contain mitochondria.

Mitochondria convert the chemical energy stored in food into compounds that are more convenient for the cell to use.


+Mitochondria

Mitochondria are enclosed by two membranes1. outer membrane 2. inner membrane.

The inner membrane is folded up inside the organelle.


+Chloroplasts

Plants and some other organisms contain chloroplasts.

Chloroplasts capture energy from sunlight and convert it into chemical energy in a process called photosynthesis.


+Chloroplasts

Chloroplasts are surrounded by two membranes.

Chloroplasts contain the green pigment chlorophyll.


+Cytoskeleton

Eukaryotic cells are given their shape and internal organization by the cytoskeleton.

The cytoskeleton is a network of protein filaments that helps the cell to maintain its shape.

The cytoskeleton is also involved in movement.

The cytoskeleton is made up of: microfilaments microtubules


+Cytoskeleton

Ribosomes Mitochondrion

Endoplasmic reticulum

Cell membrane

Microtubule

Microfilament


+Cytoskeleton Microfilaments

Microfilaments: are threadlike structures made up of the

protein actin. form extensive networks in some cells. produce a tough, flexible framework that

supports the cell. help some cells move.


+Cytoskeleton Microtubules

Microtubules are hollow structures made up of proteins known as tubulins.

Microtubules: maintain cell shape. are important in cell division. build projections from the cell surface—cilia

and flagella—that enable some cells to swim rapidly through liquids.


+Cytoskeleton Centrioles

In animal cells, structures known as centrioles are formed from tubulin.

Centrioles are located near the nucleus and help to organize cell division.

+


7-2

In the nucleus of a cell, the DNA is usually visible as a dense region called the nucleolus. the nuclear envelope. granular material called chromatin. condensed bodies called chloroplasts.

+


7-2

Two functions of vacuoles are storing materials and helping to break down organelles. assemble proteins. maintain homeostasis. make new organelles.

+


7-2

Chloroplasts are found in the cells of plants only. plants and some other organisms. all eukaryotes. most prokaryotes.

+


7-2

Which of the following is NOT a function of the Golgi apparatus? synthesize proteins modify proteins sort proteins package proteins

+


7-2

Which of the following is a function of the cytoskeleton? manufactures new cell organelles assists in movement of some cells from one place to

another releases energy in cells modifies, sorts, and packages proteins

+Microscopy

+How do we study cells?

The invention of the microscope led to the discovery of the cell.

Light microscopes can magnify images up to 1,000 times the actual size.

At higher magnifications, the image blurs and more efficient microscopes are necessary.

+Microscopes

Microscopes vary in magnification and resolving power. Magnification is the ratio of an object’s

image to its real size. Resolution is the ability to distinguish

between 2 points. Resolution is limited by the wavelength of

light.

+ An visual example of how big a cell and its parts are

Magnified by a factor of 10

+Electron Microscopes Electron microscopes reveal details

1000 times smaller than those visible in light microscopes.

Electron microscopy can be used to visualize only nonliving, preserved cells and tissues.

Transmission electron microscopes (TEMs) Used to study cell structures and

large protein molecules Specimens must be cut into ultra-thin

slices

+Electron Microscopes

Scanning electron microscopes (SEMs)

Produce three-dimensional images of cells

Specimens do not have to be cut into thin slices

+

Scanning Electron micrograph of neurons

+Confocal Light Microscopes Confocal Light Microscopes scan cells with a laser

beam.

This makes it possible to build 3-D images of cells and their parts.

Confocal Light Micrograph of HeLa Cells

+Scanning Probe Microscopes

Scanning Probe Microscopes allow us to observe single atoms.

Images are produced by tracing surfaces of samples with a fine probe.

Scanning Probe Micrograph of DNA


+

Electron microscopes are capable of revealing more details than light microscopes becausea. electron microscopes can be used with live

organisms.b. light microscopes cannot be used to

examine thin tissues.c. the wavelengths of electrons are longer

than those of light.d. the wavelengths of electrons are shorter

than those of light.


+

Which organism listed is a prokaryote? a. protistb. bacteriumc. fungusd. plant


+

One way prokaryotes differ from eukaryotes is that theya. contain DNA, which carries biological

information.b. have a surrounding barrier called a cell

membrane.c. do not have a membrane separating DNA

from the rest of the cell.d. are usually larger and more complex.

+ Life on a Cellular Level Mrs. Geist Biology Fall 2010-2011.

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Transcript of + Life on a Cellular Level Mrs. Geist Biology Fall 2010-2011.