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BIL 255 CHAPTER 9 EXAM QUESTIONS AND VERIFIED ANSWERS
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BIL 255 CHAPTER 9 EXAM QUESTIONS AND VERIFIED ANSWERS...
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For a given individual, the nucleotide sequence of the genome in virtually everyone of its cells - ANSWER is the same
compare the DNA of two individuals - ANSWER the genomes of individuals
within a species contain slightly different information
between members of different species - ANSWER deviations are even more
extensive
such differences in DNA sequences are responsible for - ANSWER the
diversity of life on earth, from the subtle variations in hair colour, eye colour
and skin colour that characterize members of our own species to the dramatic
differences in phenotype that distinguish a fish from a fungus or a robin from a
rose
improvements in the methods used to sequence and analyze whole genomes are
- ANSWER now allowing us to address various questions
ability to compare the genome from a wide-ranging collection of organisms has
provided - ANSWER striking confirmation of Darwin's explanations for the
diversity of life on earth - revealing how processes of mutation and natural
selection have been sculpting DNA sequences for billions of years, giving rise
to the spectacular menagerie of present day life forms that crowd every corner
of the planet
evolution as a tinkerer than inventor - ANSWER uses raw materials in DNA
sequences that each organism inherits from its ancestors
no natural mechanism for - ANSWER making long stretches of entirely novel
nucleotide sequences
no gene or genome is - ANSWER ever entirely new
,astonishing diversity in form and function is the result of - ANSWER
variations on preexisting themes
as genetic variations pile up over millions of generations - ANSWER they can
produce radical change
mutation within a gene - ANSWER An existing gene can be modified by a
mutation that changes a single nucleotide or deletes or duplicates one or more
nucleotides
These mutations can alter the splicing of a gene's transcript or change the
stability, activity, location or interactions of its encoded protein or RNA product
mutation within regulatory DNA - ANSWER When and where a gene is
expressed can be affected by a mutation in the stretches of DNA sequence that
regulate the gene's activity
Humans and fish have a surprisingly large number of genes in common but
changes in the regulation of those shared genes underlie many of the most
dramatic differences between those species
gene duplication - ANSWER An existing gene, a larger segment of DNA or
even a whole genome can be duplicated, creating a set of closely related genes
within a single cell
As this cell and its progeny divide, the original DNA sequence and its duplicate
can acquire additional mutations and thereby assume new functions and patterns
of expression
exon shuffling - ANSWER Two or more existing genes can be broken and
rejoined to make a hybrid gene containing DNA segments that originally
belonged to separate genes
In eukaryotes, the breaking and rejoining often occurs within the long intron
sequences, which do not encode protein
Because intron sequences are removed by RNA splicing, the breaking and
joining do not have to be precise to result in a functional gene
,mobile genetic elements - ANSWER Specialized DNA sequences that can
move from one chromosomal location to another can alter the activity or
regulation of a gene; they can also promote gene duplication, exon shuffling and
other genome rearrangements
horizontal gene transfer - ANSWER A piece of DNA can be transferred from
the genome of one cell to that of another - even to that of another species
This process, which is rare among eukaryotes but common among bacteria,
differs from the usual vertical transfer of genetic information from parent to
progeny
each form of genetic variation - from the simplest mutations that occur within a
gene to the more extensive duplications, deletions, rearrangements and
additions that occur within a genome - ANSWER has played an important role
in the evolution of modern organisms
contribution of sex - ANSWER the mechanism that many organisms use to
pass genetic information on to future generations
in sexually reproducing organisms - ANSWER only changes to the germ line
are passed to progeny
bacteria and unicellular organisms - inheritance of genetic information -
ANSWER Each individual duplicates its genome and donates one copy to each
daughter cell when the individual divides in two
The family tree of such unicellular organisms is simply a branching diagram of
cell divisions that directly links each individual to its progeny and to its
ancestors
multicellular organism - inheritance of genetic information - ANSWER
Although individual cells within that organism divide, only the specialized
reproductive cells - the germ cells - carry a copy of its genome to the next
generation of organisms
, All the other cells of the body - the somatic cells - are doomed to die without
leaving evolutionary descendants of their own
Somatic cells exist only to help the germ cells survive and propagate
germ cells - ANSWER specialized reproductive cells
carry a copy of its genome to the next generation of organisms
somatic cells - ANSWER doomed to die without leaving evolutionary
descendants of their own
somatic cells exist only - ANSWER to help the germ cells survive and
propagate
mutation in somatic cell - ANSWER although it might have unfortunate
consequences for the individual in which it occurs (causing cancer) will not be
transmitted to the organism's offspring
for a mutation to be passed on to the next generation - ANSWER it must alter
the germ line - the cell lineage that gives rise to the germ cells
when we track genetic changes that accumulate during the evolution of sexually
reproducing organisms - ANSWER we are looking at the events that took
place in a germline cell
It is through a series of germ line cell divisions that - ANSWER sexually
reproducing organisms trace their descent back to their ancestors and ultimately
back to the ancestors of us all - the first cells that existed, at the origin of life
more than 3.5 billion years ago
sex - genetic change - ANSWER when germ cells from a male and female
unite during fertilization, they generate offspring that are genetically distinct
from each parent
aside from mating based genome reshuffling which influences how mutations
are inherited in organisms that reproduce sexually - ANSWER most of the
mechanisms that generate genetic change are the same for all living things
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