Genetics - Chapter 6

Question 1

Miescher

Answer 1

investigated a compound found in nucleus of cell

called this compound nuclein, now known as DNA

Question 2

Hammerling

Answer 2

verified that genetic material was in nucleus
used algae, where the nucleus is found in the foot section
when any part of the algae was cut off, that section grew back, however when the foot section was cut off, nothing grew back

Question 3

Hershey and Chase

Answer 3

worked with bacterial viruses
showed that viruses inject only their DNA into bacteria to produce more viruses, nothing else
therefore DNA directed the production of new viruses, and is the hereditary material

Question 4

Levene

Answer 4

discovered that DNA has 3 main components
pentose sugar
phosphate group
nitrogenous base (carbon-nitrogen rings)

Question 5

Watson and Crick

Answer 5

built a model of DNA
showed the molecular structure (double helix), the three different components, and the linking between A and T, and C and G
this was the final determination of the structure of DNA

Question 6

DNA

Answer 6

deoxyribonucleic acid
double helix
composed of 4 different types of nucleotides with each of the following nitrogenous bases
purines (adenine, guanine) = 2 carbon rings
pyrimidines (cytosine, thymine) = 1 carbon ring

Question 7

Pairing of nucleotides

Answer 7

nucleotides bond between DNA strands via a hydrogen bond (force acting on the nucleotides)
purines bond with pyrimidines
A = T (2 hydrogen bonds), C = G (3 hydrogen bonds)
the two strands are antiparallel, the phosphate end of one matches with the sugar end of the other

Question 8

Mutations in DNA

Answer 8

spontaneous = occurs randomly, not caused by outside factors (mistakes when DNA is copied)
induced mutations = occur because of exposure to a physical or chemical agen that causes a mutation
there are 3 means of chromosomal changes = point mutations, block mutations, chromosomal mutations

Question 9

Point mutations

Answer 9

small scale change to one nucleotide in the sequence
can have disastrous, little, or no effect on the protein coded for
substitution = different base inserted
insertion = extra base added
deletion = base removed
inversion = base order reversed

Question 10

Block mutations

Answer 10

large scale change to larger chunks of nucleotides in the sequence

Question 11

Deletion

Answer 11

part of the chromosome is actually lost
due to viruses, radiation, chemicals
may carry a specific gene which may have a large effect on the host
cri du chat = deletion of chromosome 5

Question 12

Duplication

Answer 12

gene sequence is repeated one or more times within a chromosome
at some point, too many repeats can affect the function of the gene
fragile X syndrome = form of autism and inherited intellectual disabilities in males

Question 13

Inversion

Answer 13

gene segment momentarily becomes free from its chromosome and then reinserts itself in the opposite order
this can completely alter the gene’s activities

Question 14

Translocation

Answer 14

Barbara McClintock proved that gene sequences can move from one part of a chromosome to another
these segments are referred to as transposons, or jumping genes

Question 15

Chromosomal mutation

Answer 15

large error involving the whole chromosome

example = non-disjunction

Question 16

Inheriting mutations

Answer 16

many mutations go unnoticed because they occur in parts of the DNA that do not code for genes
many others are corrected in the copying process
as a person ages, mutations occur more frequently
for a mutation to be passed on from one generation to the next, it must be located on the gametes

Question 17

Bacterial resistance

Answer 17

antibiotics destroy bacteria by binding to the cell wall and weakening it
if a bacteria has gone through a certain mutation, the antibiotic will not be able to bind to the cell wall
since this mutation is beneficial, it will be passed on to future generations

Question 18

Human Genome Project

Answer 18

13 year project to sequence the human genome and other species
initially, scientist from around the world collaborated to complete the HGP
Celera genomics, a private company headed by Craig Venter, was able to use computer technologies and private funding to “join the race”

Question 19

Patenting of genes

Answer 19

gene sequences are being patented as an incentive for drug companies, allows a larger payout if there is a discovery
this poses a problem for researchers as they cannot study certain genes without fear of being sued
there are therefore some genes that may hold cures to certain diseases, but they are not being researched due to the presence of patents

Question 20

The human genome

Answer 20

approximately 3 billion base pairs
contains coding regions and non-coding regions
coding regions = sections that actually code for a protein (genes), only 1-3% of the genome
non-coding regions = junk DNA, less understood
very little genetic variation within our species

Question 21

Genomics

Answer 21

the study of genomes and the interactions of genes that result in phenotypes
functional genomics = study of the resulting function of genes

Question 22

Mice and genomics

Answer 22

mice provide a surprisingly good model organism for humans due to their genetic similarity
knockout mice = mouse where researchers have inactivated an existing gene by replacing it with an artificial piece of DNA, which causes changes in phenotypes

Question 23

Bioinformatics

Answer 23

uses computer technology to create and analyze biological information
today we have huge databases of protein and DNA information
DNA fingerprinting = pattern of bands on a gel that is unique to each individual

Question 24

DNA banks

Answer 24

public can store blood or saliva samples for evidence
endangered species genomes stored
convicted criminal DNA is stored in many countries

Question 25

Manipulating the genome

Answer 25

appropriate sections of the genome can be manipulated to allow for mass production of valuable proteins
examples = insulin, spider silk, pest-resistant food products

Question 26

Recombiant DNA

Answer 26

DNA fragment that contains DNA from more than one source
engineered and typically used with bacterial plasmids
the desire is a plasmid that contains a section of desired DNA, or the gene of interest

Question 27

Steps of recombinant DNA

Answer 27

restriction enzymes (enzymes that snips DNA at known sequences), snip either end of the gene of interest and the plasmid
same enzyme must be used in all 3 places
results in complementary sticky ends that can anneal to combine the two pieces
recombinant DNA reinserted into bacterial cell
bacteria now replicates rapidly and multiple copies of the gene of interest are achieved