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Introduction into Introduction into Cell BiologyCell Biology

What is Life? What is a cell?

Policies

Tests will cover information in lectures, recitations, and reading assignments

2 exams count towards 80% of the final grade. Weekly problem sets count towards 20% of final grade.

Make-up exams will be given only for valid reasons

Policies

All exams are to be taken without books notes.

Please turn off your phones during class

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Intro into Cell BiologyIntro into Cell Biology

-> All living organisms are made of cells

-> Cells are the smallest living unit

Human egg cell + sperm

The cell is the basic unit of life. Microorganisms such as bacteria, yeast exist as single cells. By contrast, the human is made up of about 30 trillion cells (1 trillion = 1012), which are mostly organized into collectives called tissues. Cells are, with a few notable exceptions, small with lengths measured in micrometers (1000 μm = 1 mm)

Intro into Cell BiologyIntro into Cell Biology

What is a Cell? Cell – Basic unit of living things.

Organisms are either: Unicellular – made of one

cell such as bacteria

Multicellular – made of

many cells such as plants

and animals.

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Intro into Cell BiologyIntro into Cell BiologySingle cell organisms – Multi cell organisms

-> Single cell organisms -> Microorganisms

Bacteria Archea Yeast - Fungi

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Intro into Cell BiologyIntro into Cell BiologySingle cell organisms – Multi cell organisms

-> multi cell organisms -> higher degree or organization of cells within the organism -> specialization of cells

Human red blood cells Plant cellsHuman skin cells

The first person observe and record cells was Robert Hooke (1635–1703) who described the cella (open spaces) of plant tissues. But the colossus of this era of discovery was Anton van Leeuwenhoek (1632–1723), a man with no university education observer and recorder of the microscopic living world.

Despite van Leeuwenhoek’s Herculean efforts, it was to be another 150 years before, in 1838,the botanist Matthias Schleiden and the zoologist Theodor Schwann proposed that all living organisms are composed of cells. Their “cell theory,” which was a milestone in the development of modern biology.

Intro into Cell BiologyIntro into Cell Biology

Scientists to Remember

Robert Hooke (1665) – Observed “cells” in cork

Anton van Leeuwenhoek (1674)Father of MicroscopySaw tiny living things in pond water.

Cell History

Robert Brown discovered the nucleus in

1833. Matthias Schleiden

German Botanist Matthias Schleiden

1838 ALL PLANTS "ARE

COMPOSED OF CELLS".

Theodor Schwann Also in 1838, discovered that animals

were made of cells

Cell Theory Confirmed discoveries that all scientists

believe to be true about cells:

1. Cells are the basic unit of life.

2. All living things are made of cells.

3. New cells are produced from existing cells.

Why are cells the basic units of life?

A. The cell is the structural unit of life, All organisms is make up of cells.

B.The cell is the functional unit of organisms.

All metabolic activity is based on cells.

C. The cell is the foundation of reproduce,

and the bridge of inheritance.

D. The cell is the growing and developing basis of life

Human fetal development. (a)At 5 weeks, limb buds, eyes, the heart, the liver and rudiments of all other organs have started to develop in the embryo, which is only about 1cm long. (b)Growth and development of the offspring, now called a fetus, continue during the second trimester. This fetus is 14 weeks old and about 6cm long. (c)The fetus in this photograph is 20 weeks old. Now the fetus grows to about 30cm in length.

E. Cell (nucleus) is totipotent, which can create a new organism of the same type

As a general rule, the cells of a multicellular organism all contain the same set of genes. For animals, the first evidence that even highly specialized cell carry a full complement of genes was verified by the experiment of tadpole nuclei transplanting into unfertilized egg that had been deprived of its own nucleus. Some can develop swimming tadpoles. This is animal cloning.

An especially dramatic example of animal cloning was reported in 1997. Dolly the first animal ever cloned from a cell derived from an adult.

Dolly and her daughterThe process of cloning Dolly

Is there any practical value to such technology?

Basic properties of cells

A. Cells are highly complex and organized, capable of self-regulation;

Cells acquire and utilize energy.

B. All cells share similar structure,

composition and metabolic features:

Plasma membrane, DNA/RNA, and Ribosome.

C. Cells can capable of producing more of themselves, even grow and reproduce in culture for extended periods.

HeLa cells are cultured tumor cells isolated from a cancer patient named Henrietta Lacks in 1951. It is the first human cell to be kept in culture for long periods of time and is still used today.

Johns Hopkins univesity,in 1951

D. Cells are able to respond to stimuli via surface receptors that sense changes in the chemical environment.

Cells within plant or animal respond to stimuli less obviously than single-celled protist. But they respond. They posses receptors that interact with substances in the environment in highly specific ways. For example, the receptor on the cell surface can respond to hormones and growth factors.

The Discovery of Cells

before nucleus

true nucleus

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Internal Organization

Prokaryotes Eukaryotes

Cell membraneContain DNARibosomesCytoplasm

NucleusEndoplasmic reticulum

Golgi apparatusLysosomesVacuoles

MitochondriaCytoskeleton

Compare and Contrast

Viruses

Virus diversity

1.Viruses are pathogens first described in the late 1800s.

2. Viral structure:

a)The genetic material:

Single- or double- straded DNA orRNA.

b)obligatory intracellular parasites.

3.Viral infection types:

a)Lytic infection; b)integrated infection

4. Viral origins:

a)Viruses had to arise after their hosts evolved;

b)Viruses probably arose as fragments of host chromosomes.

5.Viroids

6.prion

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Size of the cellsThe smallest objects that the unaided eye can see are about 0.1 mm long. That means under the right conditions, you might be able to see a human Smaller cells are easily visible under a light microscope. It's even possible to make out structures within the cell, such as the nucleus, mitochondria and chloroplasts. The most powerful light microscopes can resolve bacteria but not viruses.To see anything smaller than 500 nm, you will need an electron microscope.

Cell Size Female Egg - largest cell in the human body;

seen without the aid of a microscope

Most cells are visible only with a microscope.

Microscopes Light Microscope – magnifies tiny organisms

up to 1,000 times.

-Uses light and lenses.

-We use these.

Electron Microscope – magnifies

up to a million times.

-Uses electrons.

Cells are small for 2 ReasonsReason 1: Limited in size by the ratio between their

outer surface area and their volume. A small cell has more surface area than a large cell for a given volume of crtoplasm.

Cells are Small

Reason 2: The cell nucleus can only control a

certain amount of living,active cytoplasm.

Cell Shape

Diversity of form reflects a diversity of function.

The shape of a cell depends on its function.

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Evolutionary time line

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Intro into Cell BiologyIntro into Cell BiologyDifferent Types of CellsThere are two main groups of cells, prokaryotic and eukaryotic cells. They differ not only in their appearance but also in their structure, reproduction, and metabolism. However, all of the cells belong to one of the five life kingdoms. The greatest difference lies between cells of different kingdoms. The following diagram shows the five kingdoms: monera, protista, plantae, fungi, and animalia.

In biology, evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organization, from kingdoms to species, and individual organisms and molecules such as DNA and proteins. The similarities between all present day organisms indicate the presence of a common ancestor from which all known species, living and extinct, have diverged through the process of evolution.

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Intro into Cell BiologyIntro into Cell BiologyTwo cell types - The Three Domain System

Prokaryotes

The three major divisions of the living world. The tree shown here is based on comparisons of the nucleotide sequence of aribosomal RNA subunit in the different species.

Explore

Plant vs. Animal Lab You will observe different types of plant and animal cells

under the microscope and record your observations. Gel Cells for Diffusion You will build a model of a cell to understand why cells

when they reach a certain size stop growing. Edible Model Cells Using your textbook and other resources, you will make a

model of a prokaryotic and eukaryotic cell using gelatin and other edible materials. The gelatin will represent the cell membrane/cytoplasm and other edible components will be representative of the cellular organelles.

Cell Substructure

The cell is the basic unit of life. Broadly speaking, there are two types of cells: prokaryotic and eukaryotic. Prokaryotes (eubacteria and archaea) do not have a nucleus; that is, their DNA is not enclosed in a special, subcellular compartment with a double membrane. Eukaryotic cells do have a nucleus; they are also much larger than prokaryotic cells and have numerous organelles and certain substructural elements not found in prokaryotes.

Eukaryotic Cell Substructure

Eukaryotic Cell Substructure

Plant and Animal Cells

ANIMAL CELL

Mitochondria

Structure - composed of modified double unit membrane (protein, lipid)

inner membrane infolded to form cristae

Function - site of cellular respiration ie. the release of chemical energy from foodGlucose + Oxygen ------> Carbon

Dioxide + Water + Energy (ATP)

DNA

Inter-membrane space

Cytoskeletal structures

Cells contain elaborate arrays of protein fibers that serve such functions as:

Establishing cell shape Providing mechanical

strength Locomotion (cilia,

flagella) Chromosome

separation in mitosis and meiosis

Intracellular transport of organelles

Major components of cytoskeletal system

Intermediate Filaments

Microtubules Actin filaments

www.cytochemistry.net/Cell-biology/filam.htm

Rough and Smooth Endoplasmic Reticulum•Endo means within •Plamic refers to the cytoplasm •Reticulum means a network. Thus the endoplasmic reticulum is a series of interconnected, intracytoplasmic, membrane bounded sacs.

Rough endoplasmic reticulum (RER) • appear rough due to presence of ribosomes•involved in protein synthesis.

Smooth endoplasmic reticulum (SER)•has no ribosomes •The SER is involved in

•cholesterol metabolism,•membrane synthesis, (Lipids)•Detoxification,•Ca++ storage along with other cellular processes.

VesiclesMembrane bound intracellular sacs

transport vesicles endocytotic vesicles exocytotic vesicles lysosomal vesicle secretory vesicle adipose vesicles

Golgi Apparatus/Body

Proteins are transported from the RER to the golgi apparatus and from the golgi apparatus to the plasma membrane in transport vesicles.

Lysosmes

A primary lysosome contains many enzymes

synthesized in the RER and sorted in the golgi.

Peroxisomes/Micorbodies

Organelles that contain enzymes to degrade

fatty acids and amino acids.A biproduct of this degradation is H2O2

hydrogen peroxide – highly toxic to proteins Also contain the enzyme catalase which

destroys H2O2

The enzymes are synthesized on the RER and are sorted/refined into the peroxisomes in the golgi apparatus

Nucleus

The nuclear compartment contains the chromosomes, the primary genetic material, as well as all the enzymes for transcribing chromosomal DNA into RNA, processing that RNA, and exporting it out to the cytoplasm; in addition, it contains all the transcription factors and chromatin remodeling factors required for regulating RNA transcription. It is surrounded by a double membrane, which is perforated at several thousand locations all over its surface by elaborate, protein-based pore structures (nuclear pore)

PLANT CELL

Cell Wall

Cell walls are made of specialized sugars called cellulose.

Cellulose is called a structural carbohydrate (complex sugar) because it is used in protection and support.

Cell Wall

Function help a plant keep its

shape protect the cells allow plants to grow

to great heights For smaller plants,

cell walls are slightly elastic

Plastids Large cytoplasmic

organelles found in the cells of most plants

There are three plastid categories- Leucoplasts (white or

colorless plastids that store starch granules) ,

Chromoplasts (colored plastids that store pigment molecules like cartenoids which store yellow and orange pigment)

Chloroplasts which are essential in the photosynthetic process

Leukoplasts

non-pigmentous, 2x5 µm, variable shaped plastids for storage

3 types: AMYLOPLASTS (starch), ALEUROPLAST (protein), ELAIOPLASTS (oils)

Chromoplasts Chromoplast are derived

from chloroplast. Synthesize carotenoid

pigments such as carotene or lycopene.

Found in flowers, fruit, and leaves in stress or senescence.

In flowers, carotenoid pigment enables the forming of different color, which can attract insects and other pollinators.

Chloroplasts Site of photosynthesis. 500,000 chloroplasts per

square millimeter of leave surface

Contain chlorophyll, the green pigment that absorbs energy from sunlight

Sunlight captured by chlorophyll enables carbon dioxide from the air to unite with water and minerals from the soil and create food.

Chlorophyll gives plants their characteristic green color.

DNA

How Plant and Animal Cells Differ

PLANT CELLS Cell walls present Plastids occur in

cytoplasm Lysosomes not usually

evident Centrioles present only

in cells of lower plant forms

Large vacuoles filled with cell sap

ANIMAL CELLS No cell walls No plastids are found

Lysosomes occur in cytoplasm

Centrioles always present

Vacuoles, if present, are small and contractile or temporary vesicles

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Intro into Cell BiologyIntro into Cell Biology

Cell Types

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Intro into Cell BiologyIntro into Cell Biology

Prokaryotes – Domain Bacteria

-> Single cell organisms-> Single cell organisms-> No nucleus, no compartments-> No nucleus, no compartments-> Peptidoglycan cell walls-> Peptidoglycan cell walls-> Binary fission-> Binary fission-> For energy, use organic -> For energy, use organic chemicals, inorganic chemicals, chemicals, inorganic chemicals, or photosynthesisor photosynthesis

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Intro into Cell BiologyIntro into Cell Biology

Prokaryotes – Domain Archea

-> Lack peptidoglycan-> Lack peptidoglycan-> Live in extreme environments-> Live in extreme environments Include:Include:

MethanogensMethanogensExtreme halophilesExtreme halophilesExtreme thermophilesExtreme thermophiles

-> Role in disease not well -> Role in disease not well understood—this group has only understood—this group has only recently been discoveredrecently been discovered Thermophiles growing in

Yellowstone hot springs.

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Intro into Cell BiologyIntro into Cell BiologyLife on Mars?Life on Mars?Magnified view of objects in Martian meteorite found in

Antarctica. (Archaeobacteria like?)

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Intro into Cell BiologyIntro into Cell Biology

Domain Eukaryotes

-> Plantae-> Plantae multicellular plants, cellulose cell wall, photosynthesis multicellular plants, cellulose cell wall, photosynthesis -> Fungi-> Fungi

Chitin cell wallsChitin cell wallsUse organic chemicals for energyUse organic chemicals for energyMolds and mushrooms are multicellular consisting of masses of Molds and mushrooms are multicellular consisting of masses of mycelia, which are composed of filaments called hyphaemycelia, which are composed of filaments called hyphae

-> Protists-> ProtistsProtozoa, motile via pseudopods, cilia, or flagellaProtozoa, motile via pseudopods, cilia, or flagellaAlgae, photosyntheticAlgae, photosynthetic

-> Animalia-> AnimaliaMulticellular animals, Parasitic flatworms and round worms are Multicellular animals, Parasitic flatworms and round worms are called helminthes. Microscopic stages in life cyclescalled helminthes. Microscopic stages in life cycles

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FungiFungi

Slime mold

Yeast

Intro into Cell BiologyIntro into Cell Biology

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FungiFungi

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ProtozoaProtozoa

Euglena

Amoeba

Paramecium

Intro into Cell BiologyIntro into Cell Biology

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Protozoa - AlgaeProtozoa - Algae

Intro into Cell BiologyIntro into Cell Biology

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Intro into Cell BiologyIntro into Cell BiologyViruses -> are NO living organisms -> parasites

-> Consist of DNA -> Consist of DNA or or RNA coreRNA core-> Core is surrounded by a protein coat-> Core is surrounded by a protein coat-> Coat may be enclosed in a lipid envelope-> Coat may be enclosed in a lipid envelope-> Viruses are replicated only when they are in a -> Viruses are replicated only when they are in a living host cellliving host cell-> Not cellular-> Not cellular

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Intro into Cell BiologyIntro into Cell BiologyCell growth -> cell division Cell death -> apoptosis

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Intro into Cell BiologyIntro into Cell BiologyCell Movement -> Motility -> Flagellum

Pseudomonas (3,300X) Salmonella (1200X)