Cells

Compare & Contrast: What are the differences (in terms of organelles present or absent) between prokaryotic cells and plant and animal cells?

*Animal cells:* There is: nucleus, microtubule, nucleolus, cytoplasm, mitochondrion, vacuole, vesicle, golgi apparatus, ribosomes, plasma membrane, smooth endoplasmic membrane, lysosome, rough endoplasmic membrane, centriole, nuclear pore. There isn't: chloroplast, cell wall, capsule, flagella. *Plant cells:* There is: nucleus, nucleolus, vacuole, mitochondrion, smooth endoplasmic membrane, rough endoplasmic membrane, cell wall, nuclear pore, chloroplast, cytoplasm, golgi apparatus, plasma membrane, ribosomes, microtubule. There isn't: capsule, cell membrane, flagella, centriole, vesicle. *Prokaryotic cells:* There is: capsule, flagella, DNA, cytoplasm, ribosomes. There isn't; nucleus, nucleolus, nuclear pore, vacuole, mitochondria, golgi apparatus, smooth endoplasmic membrane, rough endoplasmic membrane, centriole, plasma membrane, vesicle, cell wall, cell membrane, chloroplast.

What is the difference between prokaryotic and eukaryotic cells?

*Prokaryotic cell:* organisms that have no nucleus, or any other membrane bound organelles *Eukaryotic cell:* organisms that contain complex structures enclosed within membranes

People: Robert Hooke; Anton van Leeuwenhoek, Louis Pasteur, Robert Koch, Robert Brown.

*Robert Hooke* simple microscope physics astronomy chemistry biology geology architecture naval technology *Anton van Leeuwenhoek:* inspired by book written by Hooke designed own microscope saw living organisms in ponds, water, milk, etc. *Louis Pasteur:* microbiologist vaccination microbial fermentation pasteurization causes and preventions of diseases reduced mortality from puerperal fever created first vaccines --> rabies + anthrax germ theory of disease --> direct support "father" of microbiology *Robert Koch:* founder of modern bacteriology identified agents of tuberculosis, cholera, anthrax support for infectious diseases discoveries to public health Koch's postulates --> microorganisms *Robert Brown:* earliest description cell nucleus and cytoplasmic streaming 1st observation of Brownian motion first to recognize difference between gymnosperms + angiosperms earliest studies in palynology plant taxonomy + erection of a number of plant families plant genera and species (australian)

What two types of electron microscope ? What are their different uses?

*Transmission microscope:* can magnify a sample up to one million times. The sample must be cut extremely thin. An electron beam is directed onto the sample to be magnified and some of the electrons pass through and form a magnified image of the specimen. *Scanning microscope:* can magnify a sample up to 100,000 times. A sharply focused electron beam moves over the sample to create a magnified image of the surface. Some electrons in the beam scatter off the sample and are collected and counted by an electronic device. SEMs are particularly useful because they can produce three-dimensional images of the surface of objects.

Differentiate the plasma membrane and the organelles.

*plasma membrane:* a.k.a. cell membrane controls what goes in and out of the cell, basically protecting it; one plasma membrane in a cell; plasma membrane in oval/circle shape *Organelles:* located inside the plasma membrane and have their own separate functions; many organelles; various shapes

What are the characteristics of all living things?

1. Movement 2. Respiration 3. Metabolism (food) 4. Response (to a stimulus) 5. Reproduction 6. Homeostasis (the ability to maintain the same or stable internal environment/conditions independent on the environment)

Summarize, explain and apply the cell theory.

1.All organisms are made up of one or more cells. 2.Cells are the fundamental functional and structural unit of life. 3.All cells come from pre-existing cells. 4.The cell is the unit of structure, physiology, and organization in living things. 5.The cell retains a dual existence as a distinct entity and a building block in the construction of organisms. *OR* 1. All living organisms are composed of cells 2. The structural and functional unit of life is the cell 3. All cells arise from preexisting cells "cells from cells"

How does an electron microscope work?

A microscope that uses an electron beam to illuminate a specimen and produce a magnified image.

Parts of a light microscope?

Binocular Eyepiece Revolving Nosepiece (thing to change magnification) Objective lenses (the different magnifications) Stage clips Stage Light source Base Iris Diaphragm Lever (regulates the amount of light) Fine adjustment knob Coarse adjustment knob Arm (holds the eyepiece and nosepiece) Switch dimmer

What differences between plant and human cells did you observe?

From what we observed plant cells have a cell wall and Chloroplasts and animal cells do not have a cell wall or Chloroplast, they have a cell membrane. Also, the animals cells we looked at had a round shape and the plant cells were more stretched out, almost like rectangles. And the last thing was that the cheek cells contained lysosomes.

What was one of Purkinje's discoveries?

He is best known for his 1837 discovery of Purkinje cells, large neurons with many branching dendrites found in the cerebellum.

Who was Jan Evangelista Purkinje?

He was a Czech anatomist and physiologist. His son was the painter Karel Purkinje. He was so famous that his adress was known as "Purkinje, Europe".

Hypothesize: How would lysosomes be involved in changing a caterpillar into a butterfly.

I learned this before, I don't remember exactly but I think that lysosomes digest the larva's cells from the inside out and during that process the butterfly is forming.

Compare & Contrast a compound light microscope and an electron microscope.

Light microscope: 1. Uses a beam of light that is focused using glass lenses. 2. Magnification is moderate -- not as much as electron microscope 3. Produces a color image since it uses light 4. Can look directly at the specimen with our eyes Electron microscope 1. Uses a beam of electrons that is focused using magnets. 2. Magnification can be extremely high and show details that are not possible to see with light microscopes 3. Produces a grey-scale image because color requires visible light 4. Image must be seen on a monitor or in a photograph because we don't see electrons.

Maths in Biology: If, in the ISP microscopes, the eyepiece magnification in a light microscope is 10x, and the objective lenses have 4x, 10x, 40x, and 100x, what are the lowest and the highest magnification possible?

Lowest: 40x Higher: 400x

What is the difference between magnification and resolution?

Magnification is the process of enlarging an object by using an optical instrument. Resolution is the term that is used to describe the crispness and detail of an image. High Power Field of View = Low Power Magnification Low Power Field of View = High Power Magnification

What organelles did you observe in the lab?

Nucleus, cytoplasm, cell wall, cell membrane, vacuoles Chloroplasts, or lysosomes.

How to calculate the magnification on a light microscope?

The first lense magnifies 10 times and then just look at the magnification you chose on the objective lense and just times it by 10.

Identify the role of the nucleus in a eukaryotic cell.

The nucleus in a eukaryotic cell stores genetic information and is the site of transcription of DNA. It is essentially the control center of the cell.

Why is electron microscope capable of magnification of more than 100,000 x?

The wavelength of the electrons is thousands of times smaller than the wavelength of light. Electron microscopes which in practice achieve resolutions of a few nanometers.

In which way were the two types of plant cells you looked at different?

When we observed the unstained Elodea cell we saw that we couldn't spot the nucleus. Of course we knew there was one but our hypothesis for not seeing a nucleus was that the magnification was not high enough for us to see a it. On the other hand, when we looked at the onion cells, we could see the nucleus.

Applying Concepts: Are viruses alive? Why or why not? How is this question & answer related to human health?

Viruses are not considered alive although they have some characteristics that all living things have but they are missing others. For example; Viruses can only multiply (not reproduce) within the living cells of a host. Human health can be threatened by viruses because they multiply within a host's cells. When viruses are not in contact with a host's cells they called virions.

What cell structures or organelles were visible under the compound light microscope? What cell structures and organelles are not visible under the compound light microscope for any of the cells you observed? Why were they not visible? How do we, scientists, know about these organelles?

We observed different organelles under the compound light microscope; cytoplasm, cell wall, cell membrane, nucleus, chloroplast and something that could have been vacuoles or lysosomes. We were not able to see microtubules, centrioles, rough endoplasmic reticulum, smooth endoplasmic reticulum, plasma membrane, ribosomes, golgi apparatus, vesicle, mitochondrion and chloroplast. These structures and organelles were not visible under the compound light microscopes because they do not have a strong enough magnification. Scientist know about these organelles and structures because they use scanning electron microscopes which magnify up to 200, 000 times or transmission electron microscopes that can magnify up to 1, 000, 000 times.

Why did we use a stain when observing the cells?

We used a stain to observe some of the cells because the stain makes the components of the cells more visible.

In which way were the cheek cells and blood cells different?

When we observed red blood cells under the microscope, we saw that the center of each cell was white. This meant that the cells did not contain a nucleus otherwise the center would be dark because of the DNA nucleuses contain. But when we observed the cheek cells we saw a distinct black patch which was the nucleus of the cell.

Explain how the development and improvement of microscopes changed the study of living organisms.

Without microscopes we wouldn't know about any organisms that are smaller than what the eye can see. Now we can see viruses, bacterias... Microscopes help us to find cures for diseases and save people's lives.

Summarize the role of the endoplasmic reticulum (ER).

a. *Smooth ER*: not involved in protein synthesis; site of the synthesis of fatty acids and phospholipids; no ribosomes on its surface; creates steroids and stores ions; enzymes catalyze lots of different reactions; detoxifies poisonous substances in the liver b. *Rough ER*: surface is studded (covered) with ribosomes; secretory proteins (enzymes) are manufactured