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Question 1

why are viruses not considered to be alive?

Answer 1

they can only reproduce with a host cell

Question 2

describe the structure of viruses

Answer 2

they consist of nucleic acids (the DNA) enclosed in a protein coat and sometimes also an envelope

Question 3

what is a capsid?

Answer 3

the protein shell that encloses the genome.

Question 4

what are phages/bacteriophages?

Answer 4

viruses that infect bacteria

Question 5

what is the structure of phages?

Answer 5

They have a capsid head that encloses the genome and a bunch of protein tailpieces that help attach to the host cell. (little robots)

Question 6

what are the two reproductive mechanisms of phages?

Answer 6

the lytic cycle and the lysogenic cycle

Question 7

describe the lytic cycle

Answer 7

The phage inserts its DNA/protein into the host cell and it self-assembles to create more phages. It then bursts the cell open and releases the phages. These are called virulent phages.

Question 8

describe the lysogenic cycle

Answer 8

The viral DNA is integrated into the host’s DNA (prophage) which allows the host cell to make copies of the viral DNA. eventually, it uses the lytic cycle. These are called temperate phages.

Question 9

what are retroviruses?

Answer 9

they use reverse transcriptase (an enzyme that catalyzes transcription of retrovirus RNA) to copy their RNA genome into DNA

Question 10

What is the difference between a prophage and a provirus?

Answer 10

unlike a prophage, a provirus remains a permanent resident of the host cell.

Question 11

Why is there a higher chance of mutations in RNA viruses?

Answer 11

because they lack proofreading enzymes.

Question 12

what is a prion?

Answer 12

proteins that cause normal proteins to fold abnormally causing cellular death.

Question 13

what are the 4 factors that increase genetic diversity in sexually reproducing organisms?

Answer 13

mutations, crossing over & recombination, random assortment of chromosomes in gametes, and random union of gametes in fertilization.

Question 14

what is transformation in a bacterium?

Answer 14

the alteration of a bacterial cell’s genotype and phenotype by picking up foreign DNA from the surrounding environment

Question 15

what is transduction?

Answer 15

a process in which phages carry bacterial genes from one host cell to another.

Question 16

what is conjugation in bacteria?

Answer 16

the direct transfer of genetic material between bacterial cells that are temporarily joined through a sex pilus.

Question 17

what are F plasmids and what happens?

Answer 17

F plasmids are found in F+ cells that function as DNA donors. cells with a built-in F factor are called Hfr cells.

Question 18

What are R plasmids?

Answer 18

plasmids with resistance to various antibiotics.

Question 19

how is recombinant DNA made?

Answer 19

when nucleotide sequences from two different sources are combined in vitro into the same DNA molecule.

Question 20

what is gene cloning?

Answer 20

when scientists prepare gene-sized pieces of DNA in identical copies

Question 21

what are restriction enzymes?

Answer 21

enzymes that cut DNA molecules at specific restriction sites (zig-zag shape) to make restriction fragments that are then used to make recombinant DNA.

Question 22

What does DNA ligase do in this process?

Answer 22

seals the bonds between restriction fragments.

Question 23

what is a cloning vector?

Answer 23

the original plasmid that can carry foreign DNA into a cell

Question 24

what are the 6 steps to clone a human gene?

Answer 24

1. vector and DNA are isolated, 2. DNA is inserted into the vector, 3. DNA fragments are mixed with cut plasmids, 4. recombinant plasmids are mixed with bacteria, 5. bacteria are plated and incubated, 6. cell clones are identified.

Question 25

What is polymerase chain reaction (PCR)?

Answer 25

a process that produces many copies of a specific target segment of DNA

Question 26

how is PCR done?

Answer 26

heat the DNA to separate strands. cool to allow primers to bind to the ends. Taq polymerase adds nucleotides to the 3’ ends. repeat cycle. every cycle produces 2^n DNA.