Science 10 bio

What are the advantages of electron microscopes over optical microscopes?

- They have a higher resolution and are able to magnify things up to 2 million times. -Light microscopes only magnify up to 1000-2000 times. -This is a physical limit imposed by the wavelenght of the structures that would normally be not visible by optical microscopy. -Depending on the type of electron microscopy , it is possible to view the three-dimensional external shape of an object. (Scanning Electron Microscope, SEM)

difference between prokaryotic and eukaryotic

- prokaryotic cells do not have a nucleus and eukaryotic cells do. - prokaryotic cells lack some organelles and eukaryotic cells do not. - prokaryotic cells are not found in humans and eukaryotic cells are. - prokaryotic cells are always unicellular and eukaryotic cells are often multicellular. - prokaryotic cells reproduce/divide by binary fission and eukaryotic cells reproduce/divide by mitosis/meiosis

What do Compound Microscopes do?

-Magnify up to about 1000x. -Specimen has to be sufficiently thin and bright for the microscope light to pass through. -The specimen is mounted on a glass slide. -Not capable of producing a 3D view, even if they have two eyepieces because each one of the eyes receives the same image from the objective. The light beam is simply split in two.

What are the disadvantages of electron microscopes over optical microscopes?

-They are expensive -Hard to prepare slide sometimes have to put gold, the metal reflects the electrons. -the sample has to be dry no living things -No color -They require more training -The energy of the electron beam is very high. The sample is therefore exposed to high radiation -the space requiremtns are big. They may need a whole room. -Maintenence costs are high

Stereo Microscopes

-frequently used to observe larger, opaque specimens. They generally do not magnify as much as compound microscopes. Around 40x-70x max. They give a truly stereoscopic view. This is because the image delivered to each eye is different. Stereo microscopes do not necessarily require elaborate sample preparation

When was the first electron microscope constructed?

1931

Cytoskeleton

A

LIGHT INTENSITY CONTROL KNOB

A

OCULAR(EYEPIECE)

A

Eukaryote

A cell that contains a nucleus and membrane bound organelles.

Chromosome

A coiled structure in the nucleus that contains hereditary material.

Concentration

A measure of the amount of solute dissolved in a solvent.

How does TEM work?

An electron beam is passed through an extremely thin section of the specimen. You will get a two-dimensional cross-section of the specimen.

About this same time there was a dutch businessman who did what?

Anton van leeuwenhoek used a simple microscope to observe single celled organisms he called "animalcules"

HEAD

B

SPECIMEN HOLDER/MECHANICAL STAGE

B

ARM

C

telophase

Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei.

prophase

Chromatin in the nucleus begins to condense and becomes visible as chromosomes. The nucleolus disappears.

What are the different types of light microscopes?

Compound and stereo.

Cell membrane

Controls what enters and leaves the cell

MECHANICAL STAGE CONTROLS

D

Osmosis

Diffusion of water through a selectively permeable membrane from a high concentration to a low concentration.

COARSE FOCUS KNOB

E

FINE FOCUS KNOB

F

BASE

G

Tissue

Group of similar cells that work together to do one job.

ILLUMINATOR CONDENSER (LIGHT SOURCE)

H

Smooth Endoplasmic Reticulum

H

Microfilament

Help cells change shape; structural support

In what year did an English scientist use a compound microscope to observe cork cells?

In 1663 Robert Hooke used a compound microscope to observe cork cells.

How does SEM work?

In contrast to TEM the SEM visualized the surface structure of the specimen providing a 3-D impression.

CONDENSER

J

STAGE

K

OBJECTIVE LENSES

L

Chromatin

Long strands of DNA wrapped around proteins.

NOSEPIECE

M

Organelle

Membrane bound structure inside a cell that performs a specific function.

Diffusion

Movement of particles from an area of high concentration to an area of lower concentration.

Nuclear Envelope

N

Mitochondria

Name part B. It is a site of the catbolic process that generates ATP by extracting energy from sugars, fats + other fuels.

Cytoplasm

Name part D. It is a jellylike fluid inside the cell in which the organelles are suspended.

Centrioles

Name part E. They are close to the nucleus, rod shaped bodies made up of fine microtubules. The microtubules, during cell division, direct the formation of the spindle.

Endoplasmic Reticulum

Name part F. This is a cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another.

Nucleolus

Name part G. This is a specialized structure in the nucleus, formed from various chromosomes and active in the synthesis of ribosomes.

nuclear membrane

Name part I. This is a thin structure that surrounds the nucleus. It protects and controls what goes in and out of the nucleus

Rough Endoplasmic Reticulum

Name part J, This structure is a system of internal membranes within the cytoplasm. Membranes are rough due to the presence of ribosomes. functions in transport of substances such as proteins within the cytoplasm

Ribosome

Name part K. This cell organelle is constructed in the nucleolus and functions as a site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits.

Golgi Bodies

Name part M. This structure in a cell receives proteins and other newly formed materials from the endoplasmic reticulum are stored and then modified to suit the needs of the cell. It then packages and distributes them.

Lysosomes

Name part N. This is a vesicle that bud from the Golgi apparatus and is filled with enzymes. One function is to break down lipids, carbohydrates, and proteins from food particles, it may also break down old cell parts.

Anaerobic

Process that does not require oxygen.

Aerobic

Process that requires oxygen.

Microtubules

Provide attachment places for organelles and provide tracks for organelle movement

Cell Membrane

R

What are the two names always associated with microscopes?

Robert Hooke and Anto Van Leeuwenhoek

What are the different types of electron microscopes, (2)

Scanning electron microscopes (SEM) Transmission Electron Microscopes (TEM)

metaphase

Spindle fibers align the chromosomes along the middle of the cell nucleus

Cell Theory

States that all organisms are made up of one or more cells, the cell is the basic unit of life, and all cells come from other cells.

interphase

The cell is engaged in metabolic activity and performing its prepare for mitosis. Chromosomes are not clear yet

Photosynthesis

The chemical process where plants use the sun's energy to produce sugars (food).

What are other ways in which light microscopes and electon microscopes differ?

The extent to which each can magnify and resolve and image. light microscopes-can magnify an image to about 1000x electron microscopes can magnify images 100's of thousand if not millions of times. The magnification powers and image resolution of electron microscopes has allowed science to peer deeper and deeper into the microscopic world

When did the invention of the microscope happen?

The late 1500's

Active Transport

The movement of materials through a cell membrane using energy.

Passive Transport

The movement of materials through a cell membrane without using energy.

prometaphase

The nuclear membrane dissolves. Microtubules attach at the kinetochores and the chromosomes begin moving.

Mitosis

The process of cell division in which the nucleus divides to form two identical nuclei.

How are light microscopes and electron microscopes different?

They differ in several was, but the main difference is in the type of energy used to generate the image that is magnified.

What do light microscopes do?

They use light energy, either natural or artificial to create the magnified image being viewed.

Facilitated Diffusion

When substances transport across cell membranes using protein carrier molecules.

Organ

a collection of tissues that carry out a specialized function of the body.

Selective permeability

a process in which a membrane allows some molecules to pass through while keeping others out.

Cell's Function

a) obtain food & energy b) convert energy (eg. photosynthesis) c) construct & maintain the molecules making up the cell structure d) carry out chemical reactions e) eliminate wastes f) reproducing

cell

basic building block of all living things

IRIS DIAPHRAGM LEVER

controls how much light can pass through the condenser

The Electron Microscopes use...

electrons not photons light rays for visualiztion.

Golgi apparatus

flat disc-shaped sacs that sort, modify & replace molecules sent from the ER; the needed materials are pinched off into vesicles and sent to other parts of the cell or to the cell membrane for transport out of the cell - lysosomes are produced here

Chlorophyll

green pigment in the ch that absorbs light energy used to carry out photosynthesis.

ocular

lens you look through to view the specimen

illuminator condenser

light passes through to illuminate the specimen

attached to the condenser

location of Iris diaphragm lever

on the base

location of illuminator condenser

a lens at the top of the body

location of ocular(eyepiece)

chloroplast

makes plant green where photosynthesis takes plance

anaphase

paired chromosomes separate at the kinetochores and move to opposite sides of the cell

cytokinesis

pinching the cell into two daughter cells, each with one nucleus.

mechanical stage controls

provides movement of the slides

Cells

sustain life by performing the tasks essential for the cell to function:

field

the entire area that you see through the microscope is known as the?

Cellular Respiration

the process by which cells use oxygen to produce energy from food.

The electron microscopes and Optical (light) Microscopes don't have too many things in common. True or false

true, they are technical devices which are used for visualizing structures that are too small to see with the unaided eye. This is pretty much it. The method of method of visualizing the stuctures is very different.

upper portion of microscope that holds the ocular

what is the head of the microscope?