Biology: Cell Biology I

Front 1

Identify and explain at least two examples of adaptations that enable prokaryotes to survive in environments too harsh for other organisms.

Back 1

Adaptations include the capsule (shields prokaryotes from host's immune system), plasmids (confer 'contingency functions such as antibiotic resistance), and the formation of endospores (enable cells to survive harsh conditions and to revive when the environment becomes favorable.

Front 2

Contrast the cellular and genomic organization of prokaryotes and eukaryotes.

Back 2

Prokaryotic cells generally lack the internal compartmentalization of eukaryotic cells. Prokaryotic genomes have much less DNA than eukaryotic genomes, and most of this DNA is contained in a single ring-shaped chromosome located in a nucleoid region rather than within a true membrane-bounded nucleus. Many prokaryotes also have plasmids.

Front 3

Explain how rapid reproduction allows prokaryotes to adapt to changing environments.

Back 3

Rapid reproduction enables a favorable mutation to spread quickly through a prokaryotic population by natural selection.

Front 4

A bacterium requires only the amino acid methionine as an organic nutrient and lives in lightless caves. What mode of nutrition does it employ? Explain.

Back 4

Chemoheterotrophy; the bacterium must rely on chemical sources of energy, since it is not exposed to light, and it must be a heterotroph if it requires an organic source of carbon.

Front 5

What are the sources of carbon and nitrogen for the cyanobacterium Anabaena?

Back 5

Anabaena is a photoautotroph that obtains its carbon from CO2, As a nitrogen-fixing prokaryote, it obtains its nitrogen from N2.

Front 6

Explain how molecular systematics has greatly increased our understanding of prokaryotic phylogeny.

Back 6

Before molecular systematics, taxonomists classified prokaryotes according to phenotypic characters that did not clarify evolutionary relationships. Molecular comparisons indicate key divergences in prokaryotic lineages.

Front 7

What do syphilis and Lyme disease have in common?

Back 7

Both diseases are caused by spirochetes.

Front 8

What characteristics enable some species of archaea to live in extreme environments?

Back 8

The ability of various archaea to use hydrogen, sulfur and other chemicals as energy sources and to survive or even thrive without oxygen enables them to live in environments where more commonly need resources are not present.

Front 9

Although individual prokaryotes may be tiny, they are giants in their collective impact on Earth and its life. Explain.

Back 9

Although prokaryotes are small, mostly unicellular organisms, they play key rols in exosystems by decomposing wastes, recycling chemicals and providing nutrients to other organisms.

Front 10

Explain how the relationship between humans and B. thetaiotaomicron is an example of mutualism.

Back 10

Bacteroides thetaiotaomicron, which lives inside the human intestine, benefits by obtainingnutrients from the digestive system and by receiving protection from competing bacteria from host-produced antimicrobial compounds to which it is not sensitive. The human host benefits because the bacterium manufactures carbohydrates, vitamins and other nutrients.

Front 11

Contrast exotoxins and endotoxins.

Back 11

Exotoxins are proteins secreted by prokaryotes; endotoxins are lipopolysaccharides released from the outer membrane of gram-negative bacteria that have died.

Front 12

What features of prokaryotes make thema potential bioterrorism threat?

Back 12

Their quick reproduction can make it difficult to combat them with antibiotics, particularly as they may evolve resistance to the drugs. Some also have the ability to form endospores and withstand harsh environments, surviving until conditions become mroe favourable.

Front 13

Identify at least two ways that prokaryotes have affected you positively today.

Back 13

Eating fermented foods suchas yoghurt or cheese; receiving clean water from sewage treatment; taking prokaryote-produced medicines.

Front 14

Which type of microscope would you use to study a) the changes in shape of a living white blood cell, b) the details of surface texture of a hair, and c) the detailed structure of an organelle?

Back 14

a) Light microscope, b) scanning electron microscope, c) transmission electron microscope

Front 15

Describe at least two common characteristics of chloroplasts and mitochondria.

Back 15

Both organelles are involved in energy transformation, mitochondria in cellular respirationg and chloroplasts in photosynthesis. They are both enclosed by two or more separate membranes.

Front 16

What role do the ribosomes play in carrying out the genetic instructions?

Back 16

Ribosomes in the cytoplasm translate the genetic message, carried from the DNA in the nucleus by mRNA, into a polypeptide chain.

Front 17

Describe the composition of chromatin and of nucleoli and the function(s) of each.

Back 17

Chromatin is composed of DNA and associated proteins; it carries the cell's genetic information. Nucleoli consist of RNA and proteins and are associated with particular regions of the DNA. rRNA is synthesized and ribosomal subunits are assembled.

Front 18

Describe the structural and functional distinctions between smooth and rough ER.

Back 18

The primary distinction is the presence of bound ribosomes on the rough ER. Both ER types synthesize phospholipids, membrane proteins are all produced on the ribosomes of the rough ER.

Front 19

How do transport vesicles serve to integrate the endomembrane system?

Back 19

Transport vesicles move membranes and substances they enclose btween other components of the endomembrane system.

Front 20

Starting with a zygote, a series of five cell divisions would produce an early embryo with how many cells?

Back 20

32 cells.

Front 21

How many chromatids are in a duplicated chromosome?

Back 21

2.

Front 22

A chicken has 78 chromosomes in its somatic cells; how many chromosomes did the chicken inherit from each parent? How many chromosomes are in each of the chicken's gametes? How many chromosomes will be in each somatic cell of the chicken's offspring? How many chromosomes are in a "set"?

Back 22

39;39;78;39

Front 23

During which stages of a cell cycle would a chromosome consist of two identical chromatids?

Back 23

From the end of S phase of interphase through the end of metaphase of mitosis.

Front 24

Compare cytokinesis in animal cells and plant cells.

Back 24

In an animal cell, cytokinesis occurs by cleavage, which divides the parent cell in two with a contractile ring of actin filaments. In a plant cell, a cell plate forms in the middle of the cell and grows until its membrane fuses with the plasme membrane of the parent cell. A new cell wall is also produced from the cell plate, resultinin two daughtercells.

Front 25

What is a function of nonkinetechore microtubules?

Back 25

They elongate the cell during anaphase.

Front 26

A researcher treats cells with a chemical that prevents DNA synthesis. This treatment traps the cells in which part of the cell cycle?

Back 26

G1

Front 27

What is the go-ahead signal for a cell to pass the G2 phase checkpoint and enter mitosis?

Back 27

A sufficient amount of MPF has to build up for a cell to pass the G2 checkpoint.

Front 28

What phase of the cell cycle are most of your body cells in?

Back 28

Most body cells are not in the cell cycle, rather they are in the nondividing state called G0.

Front 29

Compare and contrast a benign tumour and a malignant tumour.

Back 29

A benign tumour stays at the original site and can usually be surgically removed. Cancer cells from a malignant tymour spread from the original site by metastasis and may impair the functions of one or more organs.