cells structure and function input from ms. thomas (ib teacher) and heinemann book

CellsCells

Structure and FunctionInput from Ms. Thomas (IB teacher) and Heinemann Book

Topic 2 Section 1: Introduction to the Topic 2 Section 1: Introduction to the CellCell

Discovery of CellsDiscovery of Cells

The invention of the lens

Robert Hooke (1665): observed a thin slice of cork (dead plant cells) with a microscope. He described what he observed as “little boxes” (cells).

Discovery of CellsDiscovery of Cells

Anton van Leeuwenhoek (1675): was the first person to observe living cells.

MicroscopesMicroscopes

Magnification: refers to the microscope’s power to increase an object’s apparent size

Resolution: refers to the microscope’s power to show detail clearly

Light MicroscopeLight Microscope

Light MicroscopeLight Microscope

Elodea - Aquatic Plant

40X 400X

Transmission Electron Microscope (TEM)Transmission Electron Microscope (TEM)

Transmission Electron Microscope (TEM)Transmission Electron Microscope (TEM)

Herpes Virus

Plant Root Cell

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

Mosquito Head

200X 2000X

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

Fly Eye

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

Inside of Stomach

Surface of TongueNeuron

Scanning Electron Microscope (SEM)Scanning Electron Microscope (SEM)

PollenYeast

Red Blood Cell, Platelet, and White Blood Cell

TEM vs. SEMTEM vs. SEM

Viruses leaving a cell

The Cell TheoryThe Cell Theory

Who developed the cell theory?– Matthias Schleiden (1838):

concluded that all plants are composed of cells

– Theodor Schwann (1839): concluded that all animals are composed of cells

– Rudolph Virchow (1855): determined that cells come only from other cells

2.1.1Out line the cell theory

The Cell TheoryThe Cell Theory

What is the cell theory?

1. All living things are composed of one or more cells.

2. Cells are organisms’ basic units of structure and function.

3. Cells come only from existing cells.

2.1.1Out line the cell theory

Functions of LifeFunctions of Life

2.1.3State that unicellular organisms

carry out all functions of

life

Growt

hMet

abolis

m

All organisms exist in either a unicellular or a multicellular form.And all organisms carry out all the functions of life. These functions include:

Functions of LifeFunctions of Life

2.1.3State that unicellular organisms

carry out all functions of

life

Response

Nutrition

homeostasis

Reprod

uction

Functions of LifeFunctions of Life

All of the functions are tied together to produce a functioning living unit

Cell DiversityCell Diversity

SizeShapeInternal Organization

Cell Diversity- Cell Diversity- SizeSize

2.1.4 Compare relative

sizes of molecules, cell

membrane thickness, viruses, bacteria,

organelles and cells, sing

appropriate SI units

Cell Diversity- SizeCell Diversity- Size

6 inches long, 5 inches wide, 3 pounds

Smallest Cells:

Longest Cells:

Ostrich Egg

Biggest Cells:

2.1.4

Cells and SizesCells and Sizes

Magnification = size of image divided by the size of the specimen

2.1.5

Limiting Cell SizeLimiting Cell Size

You may wonder why cells do not grow to larger sizes, especially since growth is one of the functions of life.– There is a factor called the surface area to

volume ratio that effectively limits the size of the cells.

– In the cell, the rate of heat and waste production and rate of resource consumption are functions of (depends on) its volume

Limiting Cell SizeLimiting Cell Size

Most chemical reactions occur in the interior of the cell and its size affects the rate of these reactions. – The surface of the cell, the membrane,

controls what materials move in and out of the cell.

• Cells with more surface area per unit volume are able to move more material in and out of the cell, for each unit volume of the cell

Limiting Cell SizeLimiting Cell Size

As the width of an object such as a cell increases, the surface are also increases but at a much slower rate than the volume– This means that a large cell has

relatively less surface area to bring in needed materials and to rid the cell of waste, than a small cell.

Limiting Cell SizeLimiting Cell Size

Because of this, cells are limited as to the size they can attain and still be able to carry out the functions of the life.

Surface Area to Volume RatioSurface Area to Volume Ratio

SA = 6 mm2

SA = 24 mm2

SA = 96 mm2

V = 1 mm3

V = 8 mm3

V = 64 mm3

SA/V = 6:1

SA/V = 3:1

SA/V = 1.5:1

V increases faster than SA

SA = 6lwV = lwh

2.1.6

Cell Diversity- ShapeCell Diversity- Shape

Cells differ widely in shape.Most cells are roughly

cuboidal or spherical.

Multi-cellular organisms show Multi-cellular organisms show emergent propertiesemergent properties

Emergent properties arise from the interaction of the component parts; the whole is greater than the sum of the parts'.

2.1.7

Cells Cells DifferentiateDifferentiate

2.1.8

Differ

entiat

ion:

Cells

within

a

multi

cellul

ar

organi

sm spe

cializ

e

their

functi

on.

Specia

lized

cells

have

switch

ed on

partic

ular

genes

(expre

ssed)

that

correl

ate to

these

specia

list f

unctio

ns.

These

specif

ic gen

e

expres

sions

produc

e

partic

ular s

hapes,

functi

ons an

d

adapta

tions

within

a

cell.

Stem cells : What they are and Stem cells : What they are and therapeutic usestherapeutic uses

2.1.92.1.10

Stem cellsStem cells

They are a population of cells within organisms that retain their ability to divide and differentiate into various cells types– In the early 1980’s, scientist found

pluripotent or embryonic stem cells in mice. These cells retain the ability to form any type of cells in a organism and can even form a complete organism

Stem cellsStem cells

When stem cells divide to form a specific type of tissue, they also produce some cells that remain as stem cells.– This allows for continual production of

a particular type of tissue. – Medical experts immediately noted the

possibilities of such cells in treating certain human diseases

Stem Cell Research and treatmentsStem Cell Research and treatments

Some of the most promising research recently has been directed towards growing large numbers of embryonic stem cells in culture so that they could be used to replace differentiated cells lost due to injury and disease.– Alzheimers, Parkinsons, diabetes

Stem Cell Research and treatmentsStem Cell Research and treatments

Besides embryonic or pluripotent stem cells, there are also tissue specific stem cells.– These cells reside in certain tissue

types and can only produce new cells of that particular tissue.

• Leukemia patients

Stem Cell Research and treatmentsStem Cell Research and treatments

There are important ethical issues involved in stem cell research.– Especially controversial is the use of

embryonic or pluripotent stem cells. – This is because the cells come from embryos

often obtained from laboratories carrying out IVF

• To gather these cells involves death of the embryo and opponents argue that this represents the taking of a human life

Where do you stand in the debate about the nature of stem cell research? How do you feel about the source of pluripotent stem cells