Cellular Biology 1

Question 1

What is the cell theory

Answer 1

A set of principles developed over time via multiple investigations. The discovery of the cell was made through the invention of the microscope between 1665-1838.

Question 2

Cell Theory

Answer 2

There are 3 major parts of the cell theory:

All organisms are made of cells.

All existing cells are produced by other living cells.

The cell is the most basic unit of life.

Question 3

Limiting factor of cell

Answer 3

Cell size is limited.

As cell size increases, it takes longer for materials to diffuse from the cell membrane to the interior of the cell

Surface area-to-volume ratio:
as a cell increases in size, the volume increases 10x faster than the surface area

Question 4

Microscopes

Answer 4

Microscopes are required to visualize cells.

Light microscopes can resolve structures that are 200nm apart. (What is a nanometer?)

10,000,000 nm = 1 cm

Electron microscopes can resolve structures that are 0.2nm apart.

Question 5

Contributors to the cell theory

Answer 5

Robert Hooke
Anton van Leeuwenhoek
Matthias Schleiden
Theodor Schwann
Rudolf Virchow

Question 6

Robert Hooke

Answer 6

First scientist to use a microscope to see cellular structure. Came up with “cell” term from looking at cork.

• English Scientist
• Used the compound microscope to observe cork
• Hooke observed that cork is composed of small, hollow compartments
• The parts prompted Hooke to think of small rooms (cells) in a monastery, so he gave them the same names :CELLS
• Investigated cork through experimenting with the compound microscope and came up with the name cells

Question 7

Anton van Leeuwenhoek

Answer 7

Helped create more power lens (270x) and discovered other living cells such as bacteria and protozoa

• Dutch Tradesmen
• Study new approaches for creating lenses to observe cloth
• Leeuwenhoek’s microscope was more powerful than Hooke’s compound microscope
• From investigating and experimenting with his microscope, Leeuwenhoek became one of the first scientists to refer to living cells when he observed an abundant number of single-celled organisms, which he called animalcules (plant & animals), swimming in a drop of pond water

Question 8

Matthias schleiden

Answer 8

• German Scientist
• Fascinated with plant cells, Schleiden used the compound microscope and studied plant cells.
• From investigating and experimenting with plants, projected plant parts are made of cells!
• Discussed what he observed with his dear friend, German scientist Theodor Schwann.

Question 9

Theodor Schwann

Answer 9

• German Scientist
• Studied plant & animal cells, and was intrigued by the similarities between the two.
• From investigating and experimenting with plant & animal cells, Schwann was able to determine that all animals are made of cells!
• Schwann published the 1st statement of the cell theory: all living things are made of cells and cell products!

Question 10

Rudolf Virchow

Answer 10

Based on his investigations and experiments, he stated that all cells come from preexisting cells, which is the 2nd part of the cell theory: all existing cells are produced by other living cells!

Question 11

Robert Hooke was the first person to see cells.

Answer 11

T

Question 12

Bacteria cells have a cell membrane.

Answer 12

T

Question 13

The Cell Theory was developed by a single scientist.

Answer 13

F

Question 14

Plant cells have cytoplasm.

Answer 14

T

Question 15

Cells taken from fungi do not have DNA.

Answer 15

F

Question 16

Cells can only come from pre-existing cells.

Answer 16

T

Question 17

It only took five years to develop the Cell Theory.

Answer 17

F

Question 18

What is a prokaryotic cell?

Answer 18

Same bacteria have a tail-like structure called a flagella, that helps it to move

A capsule surrounds tome bacteria and helps them avoid the body’s immune system

Simple cells
Bacteria
These cells do not have a nucleus, their DNA is circular and floats in the cytoplasm

Pro = before; karyon = nucleus
Relatively small 5 - 10 um
Lack membrane-bound organelles
Earliest cell type

Question 19

Characteristics of a Prokaryotic cell

Answer 19

No membrane bound organelles

DNA not enclosed in membrane bound nucleus
–> DNA is localized in a nucleoid region

Genome is one circular chromosomes

DNA is not associated with histones

Cell wall made of peptidoglycan

Divide by binary fission

Generally: Smaller & less complex than eukaryotic cells

Question 20

What are archaeas?

Answer 20

Prokaryotes

Relatively small 5 - 10 um

lack membrane-bound organelles

Usually live in extreme environments (thermophiles, halophiles)

Question 21

What is an eukaryotic cell?

Answer 21

Cells found in plants, animals, protists, and fungi.

The cell is composed of 4 main parts:
1. Cell membrane
2. Cytoplasm
3. Nucleus - “control center” of cell, DNA
4. Organelles - small structures that carry out specific functions (“little organs”)

Question 22

Characteristics of an eukaryotic cell

Answer 22

Eukaryotic cells have a nucleus

Have many membrane-bound organelles (mitochondria, vacuole, endoplasmic reticulum, ribosomes, lysosomes, plastids in plants)

DNA contained in “linear chromosomes”

Cytoplasm present
Outer boundary is cell membrane except in plant cells - well made of cellulose

Cell membrane inside wall (plants)

Some have flagella/cilia for movement

Larger, more complex

Examples: protozoans, algae, fungi, plants, animals

Question 23

the comparison traits between bacteria, archaea and eukaryotes (1)

Answer 23

Bacteria

Cell type: Prokaryotic

Cell Wall: Made of peptidoglycan

Sensitivity to antibiotics :Yes

First amino acid during protein synthesis: Formylmethionine

DNA: Mostly circular chromosome and plasmids

Histones: No

Organelles: No

Ribosomes: 70S

Question 24

the comparison traits between bacteria, archaea and eukaryotes (2)

Answer 24

Archea

Cell type: Prokaryotic

Cell Wall: Does not contain peptidoglycan

Sensitivity to antibiotics : No

First amino acid during protein synthesis: Methionine

DNA: Circular chromosome and plasmids

Histones: Yes

Organelles: No

Ribosomes: 70S

Question 25

the comparison traits between bacteria, archaea and eukaryotes (3)

Answer 25

Eukaryotic

Cell type: Eukaryotic

Cell Wall: In plants and fungi, composed of polysaccharides

Sensitivity to antibiotics : No

First amino acid during protein synthesis: Methionine

DNA: Linear chromosome, rarely plasmids

Histones: Yes

Organelles: Yes

Ribosomes: 80S

Question 26

All cells have a nucleus.

Answer 26

F

Question 27

All cells have a cell membrane.

Answer 27

T

Question 28

Eukaryote cells are the only cells to have a flagellum.

Answer 28

F

Question 29

The nucleus contains the cell’s DNA.

Answer 29

T

Question 30

Chromatin will become chromosomes.

Answer 30

T

Question 31

The nucleolus makes the cell’s DNA.

Answer 31

F

Question 32

What is the difference between prokaryotic and eukaryotic (1)

Answer 32

Small cells 5ym

Always unicellular

No nucleus or any membrane-bound organelles, such as mitochondria

DNA is circular, without proteins

Ribosomes are small (70s)

No cytoskeleton

Motility by rigid rotating flagnellum. Made of flagellin

Cell division by binary fission

Reproduction is always asexual

High variety of metabolic pathways

Question 33

What is the difference between prokaryotic and eukaryotic (2)

Answer 33

Larger cells 10ym

Often multicellular

always have nucleus and other membrane bund organelles

DNA is linear and associated with proteins to form chromatin

Ribosomes are large (80s)

Always has a cytoskeleton

Motility by flexible waving cilia or flagellae. Made of tubulin

Cell division by mitosis or meiosis

Reproduction is asexual or sexual

Common metabolic pathways

Question 34

Nucleus

Answer 34

Controls every organelle (little organ) in the cytoplasm;

contains the genetic matter necessary for cell reproduction as well as control over activity within in the cell’s cytoplasm;

responsible for the cell’s metabolism, growth, and reproduction.

Has a nuclear membrane & nuclear pores

Contains cell’s DNA in one of 2 forms

chromatin - DNA and proteins, becomes…
chromosomes -during cell division

Nucleolus-which makes the cell’s ribosomes

Question 35

mitochondria

Answer 35

Involved in cellular metabolism and respiration;

provides the principle source of cellular energy and is the place where complex,

energy-releasing chemical reactions occur continuously;

The mitochondria is sometimes called the “powerhouse” of the cell

Question 36

Ribosomes

Answer 36

the site of protein synthesis in the cell

composed of ribosomal RNA and proteins

found within the cytosol of the cytoplasm and attached to internal membranes

Make enzymes and other proteins; nicknamed “protein factories”.

Question 37

Endomembrane system

Answer 37

-a series of membranes throughout the cytoplasm

-divides cell into compartments where different cellular functions occur

1. endoplasmic reticulum
2. Golgi apparatus
3. lysosomes

Question 38

endoplasmic reticulum (1)

Answer 38

Smooth endoplasmic reticulum (SER)
functions:

synthesis of membrane lipids

calcium storage

detoxification of foreign substances

Question 39

endoplasmic reticulum (2)

Answer 39

Rough endoplasmic reticulum (RER) :

membranes that create network of channels throughout the cytoplasm

Attachment of ribosomes to the membrane gives a rough appearance

involved in the synthesis of proteins, which will be secreted and sent to lysosomes or plasma membrane

Question 40

Golgi Apparatus (body)

Answer 40

chemically processes the molecules from the endoplasmic reticulum and then packages them into vesicles; nicknamed “chemical processing and packaging center”.

synthesis of cell wall components

AKA post office.

Question 41

Lysosome

Answer 41

membrane bound vesicles containing digestive enzymes to break down macromolecules

destroy cells or foreign matter that the cell has engulfed by phagocytosis

Aka ”digestive bags”

Question 42

Cytoskeleton

Answer 42

• Helps cell maintain support & shape; movement
• Network of protein fibers found in all eukaryotic cells
• Keeps organelles in fixed locations
• Helps move materials within the cell

microtubules- hollow tubes

microfilaments-threadlike

centrioles- only in animal cells; used during cell division(paired)/cell reproduction

Question 43

Cytoskeleton fibers

Answer 43

-actin filaments – responsible for cellular contractions, crawling, “pinching”

-microtubules – provide organization to the cell and move materials within the cell

-intermediate filaments – provide structural stability

Question 44

Cell Movement

Answer 44

Cell movement takes different forms.

• Crawling is accomplished via actin filaments and the protein myosin.
• Flagella undulate to move a cell.
• Cilia can be arranged in rows on the surface of a eukaryotic cell to propel a cell forward.

Question 45

Flagella and Cilia

Answer 45

Support movement (externally)

“Tail” of the sperm that enables for the sperm to “swim” or move toward the ovum.

Hair-like processes that project from epithelial cells; help propel mucus, dust particles, and other foreign substances from the respiratory tract.

Question 46

Vacuole

Answer 46

storage area for water and other substaces, plant cells usually have a large central vacuole

There are different types of vacuoles:
- central vacuole in plant cells
- contractile vacuole of some protists
- vacuoles for storage