Lecture 1 - Exam 1

Question 1

What is cell biology?

Answer 1

The study of cell structure and function.

Question 2

What are some of the processes carried out by individual cells?

Answer 2

DNA replication and RNA transcription, organelles and their function, cell signaling, motility: independent movement, using metabolic energy, and cell division/fusion.

Question 3

Why study cell biology?

Answer 3

It is basic science, and most biotech companies come from basic science studies. There are large number of applications of cell and molecular biology to medicine, such as genome edition (CRISPR), discovery of genes in heart diseases, drugs that can interfere in cancer cell growth, etc.

Question 4

Are all known living things composed of one or more cells?

Answer 4

Yes.

Question 5

Are viruses made of cells? What about strawberries?

Answer 5

No, viruses are not made of cells. Strawberries are!

Question 6

What are some unicellular organisms?

Answer 6

Bacteria, protists, and some algae and fungi.

Question 7

What is an example of a multicellular organism?

Answer 7

Humans.

Question 8

How many cells does an unfertilized chicken egg contain?

Answer 8

Single cell. The embryo is multiple cells, but before that its is one cell (until fertilized).

Question 9

What was the critical step that differentiates present-day prokaryotes to present-day eukaryotes?

Answer 9

Acquisition of cellular compartments (organelles) that allow the development of complexity.

Question 10

What are the two types of cells?

Answer 10

Prokaryotic: lack a nuclear envelope & most have cell walls (a bit plant like).
Eukaryotic: have a nucleus that separates genetic material from cytoplasm.

Question 11

What is the difference between prokaryotic and eukaryotic chromosomes?

Answer 11

Prokaryotic chromosomes are singular circular DNA molecule.
Eukaryotes have multiple linear DNA molecules.

Question 12

Despite their differences, the ____________ govern the lives of both prokaryotes and eukaryotes.
What does this fact indicate?

Answer 12

Same basic molecular mechanisms.
This fact indicates that all present-day cells are descended from a single primordial ancestor.

Question 13

Eukaryotic cells have multiple organelles. This has allowed eukaryotes to?
A. greatly simplify their metabolism and be much more efficient than prokaryotic cells.
B. evolve cells that are smaller and more complicated than prokaryotic cells.
C. evolve cells that perform limited but specialized functions.
D. increase the efficiency of metabolic pathways by keeping them separate.

Answer 13

Both C & D.

Question 14

How big are cells?

Answer 14

1-50 um. We can fit ~ 10,000 cells in a tennis ball.

Question 15

Who discovered cells?

Answer 15

Robert Hooke in 1665 using a microscope. He analyzed a thin piece of cork with a simple light microscope. Called “cells” because looked similar to monastery rooms.

Question 16

What did Antonie van Leeuwenhoek do?

Answer 16

In 1670, invented a better microscope and was able to observe a variety of cells, including sperm, red blood cells and bacteria.

Question 17

What did Matthias Schleiden and Theodor Schwann do?

Answer 17

They performed a more systematic investigation of plant and animal tissues with the light microscope… which lead to the Cell Theory.

Question 18

What is the Cell Theory?

Answer 18

1. All living organisms are composed of one or more cells.
2. The cell is the most basic unit of life.
3. All cells arise only from pre-existing cells.

Question 19

What is the modern interpretation of cell theory?

Answer 19

1. All known living things are composed of one or more cells.
2. Hereditary information in the form of DNA and RNA is found in the cell.
3. All cells arise only from pre-existing cells by cell division.
4. Energy needed for an organism to function is made in the cell.
5. The cell is the most basic unit of life.
6. All cells have the same basic chemical composition, especially in those of similar species.
7. The activity of any organism depends upon the activity of the cells that makeup that organism.

Question 20

Given that prokaryotic cells are much simpler than eukaryotic cells, why have they not gone extinct over the course of Earth’s history?

Answer 20

Although they are structurally more simple, they still perform advanced mechanisms and continuously adapt to their environment.

Question 21

What are the 6 atoms that cells are made of?

Answer 21

Carbon, nitrogen, phosphorous, oxygen, hydrogen, and sulfer.

Question 22

What are the macromolecules of life?

Answer 22

Carbohydrates, lipids, nucleic acids, and proteins.

Question 23

What is the basic unit of carbohydrates?
What are the atoms in carbohydrates?

Answer 23

Basic unit: sugar
Atoms: C, H, & O

Question 24

What does the breakdown of carbohydrates provide?
What are they also involved in?

Answer 24

Their breakdown provides both a source of cellular energy and starting material for the synthesis of other cell components.
Also, involved in cell-to-cell adhesion and signal transduction.

Question 25

What is the basic unit of lipids?
What are the atoms in lipids?

Answer 25

Basic unit: fatty acid
Atoms: C, H, O, and P

Question 26

What do lipids provide to the cell? What do they prevent? What else?

Answer 26

Lipids provide energy, structure and cushioning to the cell.
Prevents loss of heat.
Are signaling molecules.

Question 27

What are the basic units of nucleic acids?
What are the two types?
What are the atoms?

Answer 27

Basic unit: nucleotides composed of sugar, phosphate, and a base
Two types: DNA & RNA
Atoms: C, H, O, N, & P

Question 28

What do nucleic acids do?

Answer 28

Directs and controls all activities of the cell.

Question 29

What are the basic units of proteins?
What are the atoms?

Answer 29

Basic unit: Amino acid
Atoms: C, H, O, N, and S

Question 30

What do proteins provide in the cell?

Answer 30

Proteins provide a vast array of functions in the cell including metabolism, transport, and stimulus response.

Question 31

All present-day cells are descended from?

Answer 31

A primordial ancestor. The endosymbiotic theory states that mitochondria and chloroplasts in today’s eukaryotic cells were once separate prokaryotic microbes.

Question 32

What organisms do we need to survive?

Answer 32

Cyanobacteria. Without them there would be no oxygen in the atmosphere.

Question 33

The first cell was a mix of what?

Answer 33

Archaea-bacteria mix.

Question 34

The first cell emerged when?

Answer 34

Approx. 3.8 billion years ago, 750 million years after Earth was formed.

Question 35

What is a primitive atmosphere?

Answer 35

No oxygen! Reducing conditions in the atmosphere = very reactive compounds + energy (coming from lightning).

Question 36

What were the compounds on early Earth?

Answer 36

Hydrogen sulfide, carbon monoxide, carbon dioxide, nitrogen, and hydrogen.

Question 37

Once energy had combined with the compounds on early Earth, where were the nucleic acids, phospholipids, and amino acids formed?

Answer 37

In the ocean.

Question 38

What did Stanley Lloyd Miller do?

Answer 38

His experiments showed that organic molecules could form spontaneously in conditions thought to have existed on early Earth. These molecules included amino acids. Other experiments showed that organic molecules can spontaneously polymerize. For instance, simply heating amino acids causes them to polymerize.

Question 39

What macromolecule can self replicate?

Answer 39

Nucleic acids. This is a critical characteristic of the macromolecule from which life evolved.
Altman and Cech first discovered that RNA can catalyze chemical reactions, including polymerization of nucleotides.

Question 40

So, there was a period of evolution dominated by ________.

Answer 40

RNA interactions.
RNA can serve as a template for its own replication, as well as catalyze the reactions. Consequently, RNA is believed to have been the initial genetic system in evolution.

Question 41

Are phospholipid membranes hydrophobic or hydrophilic?

Answer 41

Actually, amphipathic. One portion is hydrophobic and one portion is hydrophilic.

Question 42

When phospholipids are placed in water, what happens?

Answer 42

They spontaneously form a bilayer with the phosphate containing heads on the outside.
This bilayer means that trapping RNA molecules would have maintained them as a self-replicating unit, allowing for evolution.