Chapter 1 Flashcards
the massive amount of information contained in our_____—the deoxyribonucleic acid (DNA) found within all of our chromosomes
genome
The completed sequence, published in_____, has an accu- racy greater than 99.99%; fewer than one mistake was made in every 10,000 base pairs (bp)!
2003
The results of human genome projects have shed considerable light on basic questions,
such as (5)
how many genes we have
how genes direct the activi- ties of living cells
how species evolve
how single cells develop into complex tissues
and how defective genes cause disease
controversial example of a genetic technology is________. In 1997, Ian Wilmut and his colleagues produced clones of_____, using mammary cells from an adult animal
mammalian cloning
Sheeps
In____, the first pet was cloned, a cat named CC (for “carbon copy” or “copy cat”)
2002
The adult human body is composed of______ of cells
trillions
Most human cells contain the following:
•____ human chromosomes, found in___ pairs
• ___ meters of DNA
• Approximately_______ genes coding for proteins that perform most life functions
• Approximately_____ DNA base pairs per set of chromosomes, containing the bases A, T, G, and C
46, 23
2
22,000
3 billion
The human genome is a complete set of
human chromosomes
People have____ sets of chromosomes, one set from each parent.
two
each set of chromosomes is composed of a______ that is approximately _____nucleotide base
pairs long.
DNA sequence
3 billion
Estimates suggest that each set of chromosomes contains about ________________ genes.
22,000 protein-encoding
Humans also have a small amount of DNA in their_______, which has also been sequenced.
mitochondria
_________ provide the means of modify- ing the traits of animals and plants in ways that would have been unimaginable just a few decades ago.
genetic technologies
Certain species of jellyfish emit a “green glow” produced by a gene that encodes a bioluminescent protein called___________. When exposed to blue or ultraviolet (Uv) light, the protein emits a striking green-colored light.
green fluorescent protein (GFP)
stands as the unifying discipline in biology by allow- ing us to understand how life can exist at all levels of complex- ity, ranging from the molecular to the population level.
Genetics
is the root of the natural diversity that we observe among members of the same species and among different species.
Genetic variation
is centered on the study of genes.
Genetics
is classi- cally defined as a unit of heredity, but such a vague definition does not do justice to the exciting characteristics of genes as intricate molecular units that manifest themselves as critical contributors to cell structure and function.
gene
At the molecular level, a___ is a segment of DNA that has the information to produce a functional product.
gene
The functional product of most genes is a_______—a linear sequence of amino acids that folds into units that constitute proteins.
polypeptide
Genes are commonly described according to the way they affect______, which are the characteristics of an organism.
traits
In humans, for example, we observe traits such as
eye color, hair texture, and height
the breaking of _______ during the degradation of small molecules provides energy to drive cellular processes.
chemical bonds
four important categories of larger cellular molecules are
nucleic acids (i.e., DnA and rnA)
proteins
carbohydrates
lipids
three of these—(3)—form macromolecules that
are composed of many repeating units of smaller building blocks.
nucleic acids
proteins
carbohydrates
is the largest macromolecule found in living cells
DnA
A single DnA molecule can be composed of a linear sequence of hundreds of millions of building blocks called______!
nucleotides
are small organic molecules and they are linked to each other and form the building
blocks of DnA, which is a macromolecule.
nucleotides
is a component of chromosomes, which also contain
proteins that contribute to chromosome structure.
DnA
within a________, the chromosomes are contained in a compartment called the cell nucleus. the nucleus is bounded by a double membrane composed of lipids and proteins
that shields the chromosomes from the rest of the cell.
eukaryotic cell
—a membrane-bound compartment with a specialized function.
organelle
the ______protects the chromosomes from mechanical damage and provides a single compartment for genetic activities such as gene transcription.
cell nucleus
protects the chromosomes from mechanical damage and provides a single compartment for genetic activities such as gene transcription.
cell nucleus
(3)are organized to make a complete living cell
cellular molecules, macromolecules, and organelles
the entire collection of proteins that a cell makes at a given time is called its
proteome
are the “workhorses” of all living cells.
proteins
the protein known as___ can assemble into large structures known as microtubules, which provide the cell with internal structure and organization.
tubulin
are inserted into cell membranes and aid in the transport of ions and small molecules across the membrane
Proteins
Proteins may also function as biological motors. An interesting case is the protein known as______, which is involved in the contractile properties of muscle cells.
myosin
, which accelerate chemical reactions, are a particularly important category of proteins.
Enzymes
The___ stores the information needed for the synthesis of all proteins.
DNA
DNA is composed of a linear sequence of_______, each of which contains one of four nitrogen-containing bases:
nucleotides
adenine (A), thymine (T), guanine (G), or cytosine (C).
In the code, a three-base sequence, called a____, specifies one particular amino acid among the 20 possible choices.
Codon
The process of using a gene sequence to affect the characteristics of cells and organisms is referred to as
gene expression.
In the first step, known as ________, the DNA sequence within a gene is copied into a nucleotide sequence of ribonucleic acid (RNA).
transcription
Most genes encode RNAs that contain
the information for the synthesis of a particular polypeptide. This type of RNA is called
messenger RNA (mRNA).
During the process of ______, the sequence of nucleotides in an mRNA provides the information (using the genetic code) to produce the amino acid sequence of a polypeptide.
translation
A polypeptide folds into a _______-dimensional structure.
three
T or F
protein is a functional unit.
True
The functioning of _______ largely determines cell structure and function.
proteins
During (1), one of the DNA strands is used as a template to make an RNA strand. During (2), the RNA strand is used to specify the sequence of amino acids within a polypeptide. One or more polypeptides produce a functional protein, thereby influencing an organism’s traits.
1 transcription
2 translation
Living cells are composed of nucleic acids (DNA and RNA), proteins, carbohydrates, and lipids. The _________ largely determines the structure and function of cells
proteome
DNA, which is found within chromosomes, stores the information to make ______
proteins
A _____ is any characteristic that an organism displays.
trait
______ traits affect the appearance, form, and
structure of an organism. The color of a flower and the height of a pea plant are _____ traits. Geneticists frequently study these types of traits because they are easy to evaluate. For example, an experimenter can simply look at a
plant and tell if it has red or white flowers.
Morphological
______ traits affect the ability of an organism
to function. For example, the rate at which a bacterium metabolizes a sugar such as lactose is a _______ trait. Like morphological traits, __________ traits are controlled, in part, by the expression of genes.
Physiological
________ traits affect the ways an organism responds to its environment. An example is the mating calls of bird species. In animals, the nervous system plays a key role in governing
such traits.
Behavioral
genes are expressed at the
_______ level.
molecular
Proteins often function at the ______ level
cellular
For example, a red flower has its color because its cells make a red pigment. The trait of red flower color is an observation at the ______ level, yet the trait is rooted in the molecular characteristics of the organism’s cells
organism
A ______ is a group of organisms that maintains a distinctive set of attributes in nature.
species
The occurrence of a trait within a
species is an observation at the ______ level.
population
This term describes the differences in inherited
traits among individuals within a population.
genetic variation
For example, some people have
black hair, and others have brown hair; some petunias have white
flowers, but others have purple flowers. These are examples of
genetic variation
Such contrasting forms within a single
species are termed _____. You can easily imagine how someone
might mistakenly conclude that these frogs are not members of the
same species.
morphs
Small or large differences can occur within gene sequences. When such changes initially occur, they are called _________, which are heritable changes in the genetic material
gene mutations
Gene mutations result in ________in
which a gene is found in two or more alleles
genetic variation
gene mutations alter the expression or function of a ______ that a gene specifies.
protein
—a change in chromosome structure or number (or
both)—is also found, but this type of change is often detrimental.
Chromosome variation
The term __________ refers to
the effects of environmental variation on an individual’s traits
norm of reaction
A person with Down syndrome. She has ____ chromosomes rather than the common
number of 46, because she has an extra copy of chromosome 21.
47
Like Mendel’s pea plants, sexually reproducing species are commonly ______. This means that their cells contain two copies of each chromosome, one from each parent. The two
copies are called ______ of each other.
diploid
homologs
Most cells of the human body that are not directly involved in sexual reproduction contain 46 chromosomes. These cells
are called ______ cells.
somatic
—sperm and egg cells—contain half that number (23) and are termed ______
gametes
haploid
The term _______, or simply, ____, refers to the phenomenon that the genetic makeup
of a population can change from one generation to the next.
biological evolution
evolution
When a mutation creates a new beneficial allele,
the allele may become prevalent in future generations because the individuals carrying the allele are more likely to survive and reproduce and pass the beneficial allele to their offspring. This process is known as ________. In this way, a species becomes better adapted to survive and reproduce in its native environment.
natural selection
In 2008, a more massive undertaking, called the_______, was launched, with the goal of establishing a detailed under- standing of human genetic variation. In this international project, researchers set out to determine the DNA sequence of at least 1000 anonymous participants from around the globe.
1000 Genomes Project
2015, the sequencing of over_____ genomes was described in the journal Nature.
2500
The_______ is a complete set of human chromosomes
human genome
Dolly, the first mammal to be cloned. She was cloned from a cell of a______ (a white-faced sheep). The sheep on the right is Dolly’s surrogate mother, a______.
Finn Dorset
Blackface ewe
Andrea Crisanti and colleagues have altered mosquitoes to express GFP only in the_____ of males. This enables the researchers to distinguish males from females and sort mosquitoes by sex.
gonads
The introduction of a______ gene into laboratory mice and mosquitoes.
jellyfish
In 2008, Osamu Shimomura, Martin Chalfie, and Roger Tsien received the Nobel Prize in chemistry for the discovery and the development of____, which has become a widely used tool in biology.
GFP
help determine the shape and structure of a given cell.
Proteins
Is DNA a small molecule, a macromolecule, or an organelle?
macromolecule
Within multicellular organisms, certain proteins function in cell-to-cell recognition and signaling. For example, hormones such as_____ are secreted by endocrine cells and bind to the insulin receptor protein found within the plasma membrane of target cells.
insulin
______within most genes contain the information to direct the order of amino acids within polypeptides according to the genetic code.
DNA sequences
Which types of macromolecules are found in chromosomes?
DNA
An average-sized human chromosome is expected to carry about_____ different genes.
1000
Gene expression at the molecular level involves_______ to produce mRNA and______ to produce a poly- peptide
transcription
translation
Which of the following is not a constituent of a cell’s proteome?
a. An enzyme
b. A motor protein
c. A receptor in the plasma membrane
d. an mRNA
d. an mRNA
A gene is a segment of DNA that has the information to produce a functional product. The functional product of most genes is
a. DNA.
b. mRNA.
c. a polypeptide.
d. none of the above
c. a polypeptide
The function of the genetic code is to
a. promote transcription.
b. specify the amino acids within a polypeptide.
c. alter the sequence of DNA.
d. do none of the above.
b. specify the amino acids within a polypeptide.
The process of transcription directly results in the synthesis of
a. DNA.
b. RNA.
c. a polypeptide.
d. all of the above.
b. RNA
four levels of biological organization:
molecules, cells, organisms, and populations.
This term describes the differences in inherited traits among individuals within a population
genetic variation
alter the expression or function of a protein that a gene specifies.
gene mutations
— the surroundings in which an organism exists.
environment
A rare variation in the sequence of the_____________ gene results in a nonfunctional version of this protein.
Individuals with two copies of this rare, inactive allele cannot metabolize phenylalanine properly. Such individuals represent about 1 in 8000 births in the United States.
phenylalanine hydroxylase
phenylalanine hydroxylase
When given a standard diet containing phenylalanine, individuals with this disorder are unable to break down this amino acid.
Phenylalanine accumulates and is converted into_______, which are detected in the urine.
phenylketones
individuals manifest a variety of detrimental traits, including mental impairment, underdeveloped teeth, and foul-smelling urine.
PKU
cells contain two copies of each chromosome, one from each parent. The two copies are called_____ of each other.
homologs
spans the molecular, cellular, organism, and popula- tion levels
Genetics
underlies variation in traits. In addition, the environment plays a key role
Genetic variation
During reproduction, genetic material is passed from parents to offspring.
In many species, somatic cells are_____ and have two sets of chromosomes, whereas gametes are_____ and have a single set
diploid
haploid
refers to a change in the genetic composition of a pop- ulation from one generation to the next
Evolution
The evolutionary changes that led to the mod- ern horse genus, Equus. Three important morphological changes that occurred were
larger size, fewer toes, and a shift toward a jaw structure suited for grazing.
Gene expression can be viewed at which of the following levels?
a. Molecular and cellular levels
b. organism level
c. Population level
d. All of the above
d. All of the above
variation in the traits of organisms may be attributable to
a. gene mutations.
b. alterations in chromosome structure.
c. variation in chromosome number.
d. all of the above.
d. all of the above.
A human skin cell has 46 chromosomes. A human sperm cell has
a. 23.
b. 46.
c. 92.
d. None of the above is the number of chromosomes in a sperm cell.
a. 23.
Evolutionary change caused by natural selection results in species with
a. greater complexity.
b. less complexity.
c. greater reproductive success in their native environment.
d. the ability to survive longer.
c. greater reproductive success in their native environment
Which of the following is not a model organism?
a. Mus musculus (laboratory mouse)
b. Escherichia coli (a bacterium)
c. Saccharomyces cerevisiae (a yeast)
d. Sciurus carolinensis (gray squirrel)
d. Sciurus carolinensis (gray squirrel)
A person studying the rate of transcription of a particular gene is
working in the field of
a. molecular genetics.
b. transmission genetics.
c. population genetics.
d. None of the above is correct.
a. molecular genetics.
The scientific method involves which of the following?
a. The collection of observations and the formulation of a hypothesis b. Experimentation
c. Data analysis and interpretation
d. All of the above
d. All of the above
