BIO EXAM 3 Flashcards
1
Q
- DNA contains the information needed for an organism to develop, survive, and reproduce. To carry out these functions, DNA sequences must be converted into
A
messages that can be used to produce proteins, which are the complex polymers that do most of the work in our bodies (e.g., enzymes)
2
Q
- The nucleotides in DNA and RNA have three components: a sugar group, a nitrogenous base, and a phosphate group. Adjacent nucleotides in nucleic acid are joined by a phosphodiester bond. This bond links the phosphate group of one nucleotide to which one of the following components of a neighboring nucleotide a) sugar b) base c) phosphate group
A
A. Sugar
3
Q
- Each end of DNA molecule has a number. One end is referred to as 5’ (five prime) and the other end is referred to as 3’ (three prime). The 5’ and 3’ labels refer to
A
the number on the carbon atom in a deoxyribose sugar molecule to which a phosphate group bonds.
4
Q
- Antiparallel Definition. In biochemistry, two biopolymers are antiparallel if they run parallel to each other but with opposite directionality (alignments). An example is
A
the two complementary strands of a DNA double helix, which run in opposite directions alongside each other.
5
Q
- DNA is composed of four nucleotides while proteins contain
A
20 distinct amino acids.
6
Q
- DNA is a nucleic acid composed of nucleotides: a) 5-carbon sugar called deoxyribose b) Phosphate group (PO4) c) Nitrogenous base d) All the above
A
D. All the above
7
Q
- Phosphodiester bond. The Bond between adjacent nucleotides. Formed between the phosphate group of one nucleotide and the 3′ —OH of the next nucleotide. The chain of nucleotides has a _____ orientation.
A
5’ to 3’
8
Q
- Erwin Chargaff determined that: ALL FACTS
a) always an equal proportion of two-ringed purines (A and G)
b) always an equal proportion of single-ringed pyrimidines (C and T)
c) Amount of adenine = amount of thymine (AT)
d) Amount of cytosine = amount of guanine (CG)
A
All are facts
9
Q
- The pattern of base-paring is complementary: ALL FACTS
a) A forms two hydrogen bonds with T
b) G forms three hydrogen bonds with C
A
All are facts
10
Q
- Semiconservative model – daughter strands each consist of
A
one parental strand and one new strand.
11
Q
In this model, the two strands of DNA unwind from each other, and each act as a template for synthesis of a new, complementary strand. This results in
A
two DNA molecules with one original strand and one new strand.
12
Q
DNA polymerases match existing DNA bases with complementary nucleotides and links them, that is build new D N A strands, and a) Synthesize in 5′-to-3′ direction. b) Require an primer of RNA
A
All the above
13
Q
Prokaryotic Replication. E. coli used as model system for understanding universal attributes of replication. a) Single circular molecule of D N A b) Replication begins at the origin of replication. c) Proceeds in both directions around the chromosome. d) Replicon – D N A controlled by an origin. e) All the above
A
E. All the above
14
Q
- DNA Polymerase III is a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules. Nucleic acids are
A
polymers, which are large molecules made up of repeating monomers (nucleotides) that are chemically bonded together.
15
Q
- E. coli has three D N A polymerases. D N A polymerase I (Pol I) Acts on the lagging strand to
A
remove primers and replace them with DNA.
16
Q
. DNA polymerase II (Pol II) is involved in
A
D N A repair processes.
17
Q
DNA polymerase III (Pol III) is the
A
Main replication enzyme.
18
Q
DNA is always synthesized in the 5’-to-3’ direction, meaning that nucleotides are added only to the
A
3’ end of the growing strand.
19
Q
In addition to adding nucleotides to a growing D N A strand, some polymerase molecules can
A
remove nucleotides, acting as nucleases.
20
Q
Some Polymerase molecules can remove nucleotides, acting as nucleases, a) some polymerases can be endonucleases (cut DNA internally) b) some polymerases can be exonucleases (remove nucleotides from end of DNA)
A
All the above
21
Q
Helicases use energy from A T P to
A
unwind DNA.
22
Q
Single-strand-binding proteins (SSBs) coat strands to keep them apart. the Unwinding of DNA introduces a strain in the molecule that can lead to
A
additional twisting of the helix, called supercoiling.
23
Q
DNA gyrase is
A
the Topoisomerase involved in DNA replication that relieves torsional strain.
24
Q
DNA fragments on the lagging strand are called
A
Okazaki fragments.
25
What Is the RNA Primer? An RNA primer is a
short segment of single-stranded RNA used as a binding site for DNA polymerase to initiate DNA replication. process
26
Replication fork is a
partial opening of helix formed where double stranded D N A is being unwound.
27
DNA ligase joins
Okazaki fragments to form complete strands
28
28. Telomerase is an enzyme that synthesizes the telomere repeat sequences at the ends of strand. Telomeres are the physical ends of eukaryotic chromosomes. They protect chromosome ends from DNA degradation. Telomeres are maintained by
the enzyme telomerase.
29
29. Can telomerase reverse aging? Telomere length, a marker of cellular aging, decreases with age and it has been associated with aging-related diseases. Environmental factors, including diet and lifestyle factors, affect the rate of telomere shortening which
can be reversed by telomerase.
30
30. What causes thymine dimers? Specific repair mechanism.
UV light where adjacent thymine become covalently linked together
31
31. Photolyases are DNA repair enzymes that repair damage caused by exposure to ultraviolet light. The DNA repair mechanism involving photolyases is called.
photoreactivation
32
32. Bacteria divide involves which of the following. a) binary fission b) an asexual life cycle. c) a single, circular bacterial chromosome d) replication that proceeds in two directions e) at that septum forms to divide the cell into two cells. f) all the above
F. All the above
33
33. A karyotype is. a) an individual's complete set of chromosomes b) Humans are Diploid (2n). 2 complete sets of chromosomes. c) humans have 46 total chromosomes.
A. An individuals complete set of chromosomes
34
34. Haploid (n). One set of chromosomes, 23 in humans, Pair of chromosomes are
homologous. Each one is a homologue
35
35. Chromosomes are composed of. a) Chromatin (a complex of DNA and histone proteins) b) 40% DNA, 60% histone protein c) histone is positively charged. DNA is negatively charged. d) proteins may affect the control of gene expression. e) All the above
E. All the above
36
36. What is a chromatid? A chromatid is. a) one of the two identical halves of a chromosome that has been replicated in preparation for cell division. b) The two “sister” chromatids are joined at a constricted region of the chromosome called the centromere.
A. One of the two identical halves of a chromosome that has been replicated in preparation for cell division.
37
37. The eukaryotic cell cycle proceeds as follows. (Beginning to end). a) GI, S, G2, M, Cytokinesis b) Growth Phase, replication of DNA, Replication of Organelles, Mitosis, cytokinesis c) All the above is correct.
C. All the above
38
Mitosis is divided into several phases. Which of the following are not included in mitosis? a) prophase b) anaphase c) interphase d) metaphase e) telophase
C. Interphase
39
Cytokinesis…
cleaves the cell into equal halves
40
The Cell-Cycle Control System Triggers the Major Processes of the Cell Cycle. a) The control system can arrest the cell cycle at specific checkpoints. b) The cell-cycle control system is based on activated protein kinases. c) all the above d) none of the above
C. All the above
41
Cyclins are a family of proteins that have no enzymatic activity of their own but activate cyclin-dependent kinases CDKs by binding to them. Cyclins drive the events of the cell cycle by
partnering with a family of enzymes called the cyclin-dependent kinases (Cdks).
42
Cancer is the Unrestrained, uncontrolled growth of cells, and involves. a) failure of cell cycle control b) mutated tumor-suppressor genes c) mutated proto-oncogenes d) all the above e) none of the above
D. All the above
43
Proto-oncogenes are involved in normal cell growth. Mutations (changes) in a proto- oncogene may cause it to become an oncogene, which can cause the growth of cancer cells. Normal cellular genes that become oncogenes when mutated oncogenes can cause cancer. T or F
True
44
Tumor-suppressor genes include p53 gene, 2hich is associated with the following activity. a) p53 protein monitors the integrity of DNA. b) If DNA is damaged, cell division is halted, and repair enzymes stimulated. c) If DNA damage is irreparable, p53 directs cell to kill itself. d) P53 prevents the development of many mutated cells. e) p53 is absent or damaged in many cancerous cells. f) all the above
F. All the above
45
45. Edouard van Beneden proposed that an egg and a sperm, each containing half the complement of chromosomes found in somatic cells, fuse to produce a single cell called a(n) _________blank. a) zygote b) karyotype c) embryo d) oocyte
A. Zygote
46
blank is a process of nuclear division that reduces the number of chromosomes per cell from 2 sets to1 set. a) mitosis b) meiosis c) binary fission
B. Meiosis
47
_________blank cells contain one set of chromosomes. a) germline b) somatic c) diploid d) haploid
D. Haploid
48
In life cycles that alternate between haploid and diploid stages, fertilization doubles the number of chromosomes per cell while ____blank reduces it in half. a) mitosis b) meiosis c) binary fission d) syngamy
B. Meiosis
49
Homologous chromosomes pair along their length during prophase I of meiosis. While two homologues are paired, genetic exchange may occur between them in a process called _________blank . a) syngamy b) synapsis c) independent assortment d) crossing over
D. Crossing over
50
Compared to asexual reproduction, the main advantage of sexual reproduction is. a) it requires less energy. b) it increases the genetic diversity of the offspring. c) it can produce more complex offspring. d) it can produce a greater number of offspring.
B. It increases the genetic diversity of the offspring
51
Topoisomerases are
enzymes that prevent supercoiling.
52
Evidence of crossing over can often be seen under the light microscope as a structure called a _________blank . a) kinetochore b) centromere c) centriole d) chiasma
D. Chiasma
53
The fusion of a male gamete with a female gamete is called. a) syngamy. b) meiosis. c) mitosis. d) recombination. e) synapsis.
A. Syngamy
54
Diploid organisms use meiosis to
produce haploid cells.
55
The Zygote has a) one copy of each chromosome. b) one full haploid complement of chromosomes. c) chromosomes identical to those of a sperm cell. d) chromosomes identical to those of an egg cell. e) two copies of each chromosome.
E. Two copies of each chromosome
56
All animal cells are diploid except a) gametes. b) muscle cells. c) nerve cells. d) germ-line cells. e) somatic cells.
A. Gamates
57
Which of the following processes produces new cells that are genetically identical to the original cell? a) meiosis b) mitosis c) crossing over d) independent assortment e) fertilization
B. Mitosis
58
When chromosomes of the same type are lined up. Crossing between homologous chromosomes takes place during. Crossing over is a cellular process that happens during a) meiosis 1 b) meiosis 11 c) mitosis 1 d) mitosis 11 e) none of the above
A. Meiosis
59
The term for one of a pair of chromosomes with similar genetic information and from different sources like the sperm and egg is _________blank. a) chiasma b) homologue c) kinetochore d) synapsis e) synaptonemal
B. Homologue
60
Which structure holds two homologous chromosomes together? a) Centromere b) Kinetochore c) Polar microtubules d) Spindle apparatus e) Synaptonemal complex
A. Centromere
61
You are studying meiosis in an organism where 2n = 24. How many chromosomes will each nucleus have after meiosis II is complete? a) 24 b) 12 c) 6 d) 48
B. 12
62
In 95% of cases of Down's syndrome, there is one extra chromosome (number 21) in every cell. This aneuploid condition is the result of
trisomy
63
Definition of autosomes. Of the 23 pairs of human chromosomes, 22 pairs are homologous and are found in both males and females. These are called _________blank. a) bivalents b) autosomes c) recombinant chromosomes d) somatic chromosomes e) definition of sex-linked traits
B. Autosomes
64
Traits that are controlled by genes located on the X chromosome are said to be a) autosomal b) gametal c) sex-linked d) pleiotropic
C. Sex linked
65
Allele pairs are most likely to assort independently of one another when. Occasionally, chromosomes fail to separate during meiosis, leading to daughter cells that have an atypical number of chromosomes. This phenomenon is called. a) epistasis. b) nondisjunction. c) crossing over. d) pleiotropy. e) chromosome inactivation.
B. Non disjunction
66
65. In humans, individuals with trisomy of the _________blank chromosome are most likely to survive until adulthood. a) 3rd. b) 13th. c) 15th. d) 18th. e) 21st.
E. 21st
67
In sickle cell anemia, the hemoglobin differs from typical hemoglobin by a) the color of the pigment. b) the size of the molecule. c) a single amino acid substitution. d) the total number of amino acids. e) the type of blood cell it is found in.
C. A single amino acid substitution
68
_________blank is a human hereditary disease that is caused by a dominant allele but does not show up in affected individuals until they are middle age. a) Cystic fibrosis b) Sickle cell anemia c) Tay-Sachs disease d) Huntington's disease e) Hemophilia
D. Huntingtons disease
69
Amniocentesis is a procedure that is normally used. a) to reduce the risk of genetic disease. b) for gene therapy. c) to change the sex of the fetus. d) for diagnosis of genetic disorders. e) to nourish the fetus.
A. To reduce the risk of genetic disease
70
69. The Chromosomal Theory of Inheritance states that chromosomes are the vehicles of genetic heredity. a) Mendelian Genetics is perfectly accurate b) Gene Linkage is perfectly accurate. c) chromosome behavior also involves segregation. d) chromosome behavior also involves independent assortment. Both are true
BOTH ARE TRUE
71
70. Mendelian Inheritance refers to the
inheritance of traits controlled by a single gene with two alleles, one of which may be completely dominant to the other.
72
71. Linkage, as related to genetics, refers to the closeness of genes to one another on the same chromosome. The closer two genes or sequences are to each other on a chromosome,
the greater the probability that they will be inherited together
73
72. With his work on pea plants, Mendel discovered the fundamental laws of inheritance. He reasoned that
genes come in pairs and are inherited as distinct units, one from each parent.
74
73. Mendel described a gene as a discrete unit of heredity that influences a visible trait. Parents transmit discrete factors (genes) a) everyone receives one copy of a gene from each parent. b) not all copies of a gene are identical. c) Allele: alternative form of a gene d) Homozygous: 2 of the same alleles e) Heterozygous: different alleles f) all of the above
F. All the above
75
74. The presence of allele does not guarantee expression. a) Dominant allele – expressed. b) Recessive allele – hidden by dominant allele. c) Genotype – an individual’s complete set of alleles d) Phenotype – an individual’s physical appearance, based on the genotype. F) all of the above
F. All the above
76
75. The law of segregation states that everyone that is a diploid has a pair of alleles (copy) for a particular trait. Each parent passes an allele at random to their offspring resulting in a diploid organism. The allele that contains the dominant trait determines
the phenotype of the offspring.
77
76. Environment effects Phenotype. Phenotypic plasticity refers to
different phenotypes from the same genotype due to environmental conditions.
78
Often, the phenotype is the result of
an accumulation of contributions by multiple genes. However, most traits due to single genes
79
Incomplete Dominance means that
heterozygote is intermediate in phenotype between the two homozygotes. For example, red flowers × white flowers = pink flowers T or F
80
In Codominance, the heterozygote shows
some aspects of the phenotypes of both homozygotes.
81
Epistasis is when
the action of one gene obscures the effects of another gene.
82
81. A B O blood groups illustrate
both codominance and multiple alleles.
83
A Test Cross is
an experimental cross of an organism’s genotypes and the resulting phenotype, based on the concepts of dominant genotype and recessive genotype.
84
Humans have 46 total chromosomes, and 22 pairs are
autosomes (non-sex chromosomes).
85
In organisms with X Y sex-determination (like humans) few genes from
Y chromosome are expressed
86
A Recessive Allele on X chromosome have no active partner on Y, therefore, a single recessive sex-linked gene can produce recessive phenotype. Certain genetic diseases affect males to a greater degree than females as a result. a) X-linked recessive alleles b) red-green color blindness c) hemophilia d) all of the above
D. All the above
87
Genes from mitochondria and chloroplasts are often passed to the offspring by
only one parent, often the mother, called maternal inheritance.
88
In genomic imprinting, the phenotype exhibited by a mutant allele depends on
which parent contributed the allele to the offspring.
89
Epigenetic Inheritance is an unconventional finding. It goes against the idea that inheritance happens only through the DNA code that passes from parent to offspring. It means that a parent's experiences can be
passed down to future generations. It is a change in gene function that does not involve a change in DNA sequence.
90
Human Genetic Disorder Causes. A single amino acid change in a single protein can result in clinical syndrome. For Example: Sickle Cell Anemia. First human disease shown to be the result of a mutation in
a protein. Caused by a defect in the oxygen carrier molecule, hemoglobin Leads to impaired oxygen delivery to tissues.
91
Nondisjunction changes chromosome number. Nondisjunction is the failure of homologues or sister chromatids to separate properly during meiosis. a) aneuploidy – gain or loss of a chromosome, the result of nondisjunction b) monosomy – loss c) trisomy – gain d) all the above
D. All the above
92
Human Genome Maps, we can use data derived from historical pedigrees and we use data from disease-causing (that is tracible) alleles (these are both difficult). However, maps can be improved using
molecular techniques (advanced DNA & protein analysis).
93
As the name implies, short tandem repeat (STR) analysis is a method of determining an individual's DNA profile by
counting the number of times a small DNA sequence (short tandem repeat unit) is repeated at a specific chromosomal location.
94
Single-nucleotide polymorphisms (SNPs). (SNPs) are caused by point mutations that give rise to
different alleles containing alternative bases at a given position of nucleotide
95
SNPs occur frequently throughout the genome. Therefore, they can be used as markers to identify disease-causing genes. Two closely located alleles (gene and marker) are
inherited together
96
A Marker (synonymous with the word “landmark” and often referred to as a genomic marker or a genetic marker) is
a DNA sequence, typically with a known location in a genome.
97
The Human Genome Project is one of the greatest scientific feats in history. The DNA (genome) project began in1990 and was completed in 2003. The Project’s main accomplishment provided fundamental information
about the human blueprint, which has advanced the study of human biology and improved the practice of medicine
98
Pedigree Map – e.g., sickle cell anemia Definition Pedigree Map: A diagram of family history that uses standardized symbols. A pedigree shows
relationships between family members and indicates which individuals have certain genetic disease- causing variants (genotype) traits (phenotype) p
