CH1 | Introduction to Molecular Biology Flashcards
Molecular biology studies…
cellular biochemical and molecular processes.
Nucleic acids are macromolecules made of…
nucleotides.
Nucleic acids function to…
store and transmit genetic information and regulate protein synthesis.
The two classes of nucleic acids are…
DNA and RNA.
DNA stands for…
deoxyribonucleic acid.
RNA stands for…
ribonucleic acid.
The three components of a nucleotide are…
phosphate group, pentose sugar, nitrogenous base.
The phosphate group in nucleotides is…
the same in both DNA and RNA.
The pentose sugar in DNA is…
deoxyribose.
The pentose sugar in RNA is…
ribose.
Difference between ribose and deoxyribose is…
2’ carbon in ribose is -OH, 2’ carbon in deoxyribose is -H
The nitrogenous bases in DNA are…
adenine, guanine, cytosine, thymine.
The nitrogenous bases in RNA are…
adenine, guanine, cytosine, uracil.
Adenine and guanine are classified as…
purines.
Cytosine, thymine, and uracil are classified as…
pyrimidines.
In RNA, the base that replaces thymine is…
uracil.
Purines are characterized by…
a double-ring structure.
Pyrimidines are characterized by…
a single-ring structure.
Nucleobase is also known as…
a nitrogenous base.
A nucleoside is made of…
nucleobase + sugar.
A nucleotide is made of…
nucleoside + phosphate.
DNA is described as being…
double-stranded, complementary, and antiparallel.
Double-stranded means…
two strands of nucleotides.
Complementary means…
bases pair up according to specific rules (A-T, C-G).
Antiparallel means…
the two strands run in opposite directions (5’ to 3’ and 3’ to 5’).
DNA has directionality, which is…
5’ to 3’.
In DNA, A bonds with…
T (via 2 hydrogen bonds).
In DNA, C bonds with…
G (via 3 hydrogen bonds).
DNA forms a double helix because…
the nucleotides of the two strands wrap around each other.
RNA is typically…
single-stranded.
RNA carries genetic information from…
DNA in the nucleus to the cytoplasm.
RNA’s primary function is to…
build proteins.
The two main categories of RNA are…
coding and non-coding RNA.
mRNA is a type of…
coding RNA.
tRNA, rRNA, lncRNA are types of…
non-coding RNA (ncRNA).
miRNA, snoRNA, siRNA, snRNA are types of…
small ncRNA.
The four nucleobases of RNA are…
Uracil, Cytosine, Adenine, Guanine.
A gene is a section of…
DNA.
Genes contain instructions for…
building proteins.
Genes store information that is…
passed down through generations.
Gene size varies from…
a few hundred bp to over 2 million bp.
“bp” in the context of genes stands for…
base pairs.
The Human Genome Project estimated that humans have about…
20,687 protein-coding genes.
Genes are located in the…
cell nucleus.
Gene is part of a structure called…
chromosome.
Eukaryotic genes’ structure consists of…
an upstream regulatory sequence, an open reading frame and a downstream regulatory sequence.
The open reading frame (ORF) contains…
exons and introns.
Exons are…
protein-encoding DNA sequences (1.5%).
Introns are…
non-coding segments removed by splicing (>98%).
The 5’ upstream regulatory sequence contains the…
promoter region.
The promoter region controls…
gene expression.
The 3’ downstream regulatory sequence regulates…
termination of gene expression.
Enhancer/Silencer regions are located in…
distal control elements (upstream or downstream)
Terminator sequence are located in…
downstream regulatory sequence.
TATA box is located in…
promoter region.
Poly-A tail is located in…
downstream regulatory sequence (after the last exon).
An organism’s full set of genes is called the…
genome.
Humans have approximately … base pairs.
3 billion
Humans have a total of … chromosomes, … from each parent.
46, 23
Humans have approximately … base pairs.
3 billion
Different forms of genes are called…
alleles.
Alleles are…
Different forms of the same gene.
A fixed position on a chromosome where a gene is located is called a…
locus (loci).
Locus is…
the specific location of a gene on a chromosome.
Homologous chromosomes are…
chromosome pairs, one from each parent.
Homozygous means…
having two identical alleles for a gene.
Heterozygous means…
having two different alleles for a gene.
Humans have … chromosomes in every cell.
46
Autosomes (1-22) are…
diploid.
Diploid means…
having two sets of homologous chromosomes.
Haploid means…
having a single set of unpaired chromosomes.
The number and visual appearance of the chromosomes in the cell nuclei of an organism or species is called…
a karyotype.
When not being replicated or transcribed, DNA is stored in…
thread-like structures inside the nucleus.
DNA is packaged to…
protect it and aid in DNA replication.
Chromosomes have a constricted region called the…
centromere.
The ends of chromosomes are called…
telomeres.
Chromosomes have a short arm called the…
p arm.
Chromosomes have a long arm called the…
q arm.
Based on centromere position, the 4 types of chromosomes are…
metacentric, submetacentric, acrocentric, telocentric.
Telomeres are located at…
the ends of chromosomes.
Telomeres are made of…
non-coding repetitive DNA sequences.
The specific DNA sequence of telomeres is…
5’-TTAGGG-3’.
Telomeres function to…
maintain chromosome structural integrity.
Telomeres prevent attack by…
enzymes.
As cells divide, telomeres…
shorten.
Telomere shortening eventually leads to…
cell senescence (cell stops dividing).
DNA replication is the process by which a cell…
makes an identical copy of its DNA.
DNA replication is essential for…
the transmission of genetic information to the next generation.
In eukaryotic cells, DNA replication occurs in the…
nucleus.
In prokaryotic cells, DNA replication occurs in the…
cytoplasm.
DNA replication occurs during the…
S phase of interphase.
During the cell cycle, DNA Synthesis happens in the…
S phase.
Interphase consists of…
G1, S, and G2 phases.
DNA replication is described as…
semi-conservative.
Semi-conservative replication means…
each new DNA molecule has one old strand and one new strand.
Each strand in a DNA molecule serves as a…
template for synthesis of a new, complementary strand.
Template strand is…
the original DNA strand used to synthesize a new strand.
Complementary strand is…
the new DNA strand synthesized using the template strand.
Semi-conservative replication ensures that…
genetic information is accurately transmitted to the next generation.
Semi-conservative replication allows for genetic variation through…
mutations during DNA replication.
The three stages of DNA replication are…
initiation, elongation, and termination.
DNA replication begins at specific locations called…
origins of replication.
The origin of replication is located by…
pre-replication protein complexes.
The enzyme that temporarily breaks the DNA backbone to unwind it is…
topoisomerase.
The enzyme that unwinds DNA by breaking hydrogen bonds is…
helicase.
The enzyme that “unzips” the DNA is…
helicase.
Proteins that stabilize the unwound DNA are…
single-stranded binding proteins (SSBs).
The Y-shaped structure formed during initiation is called the…
replication fork.
During replication, each DNA strand acts as a…
template that is replicated differently.
In DNA replication, new nucleotides are added in the … direction.
5’ to 3’
The enzyme that adds a short RNA primer to start replication in the leading strand is…
primase.
The leading strand is synthesized…
continuously, towards the replication fork.
The enzyme that adds new nucleotides to the leading strand is…
DNA polymerase (δ and ε).
The lagging strand is synthesized…
discontinuously, away from the replication fork.
The short DNA fragments synthesized on the lagging strand are…
Okazaki fragments.
On the lagging strand, numerous … are needed.
RNA primers.
Okazaki fragments are approximately … base pairs long.
100-200
The enzyme that removes RNA primers is…
RNase H.
After RNA primer removal, the gap is filled by…
DNA polymerase.
The enzyme that joins Okazaki fragments is…
DNA ligase.
DNA ligase joins Okazaki fragments by forming…
phosphodiester bonds.
The role of DNA ligase is to…
connect DNA fragments by forming phosphodiester bonds between them.
Exonuclease is…
an enzyme that removes RNA primers (e.g. RNase H).
At the end of replication, the lagging strand is…
shorter than the leading strand.
The RNA primer at the end of the lagging strand cannot be replaced with DNA because…
there is no free 3’ OH group for DNA polymerase to add to.
The end replication problem leads to a gap in the…
newly synthesized DNA strand at the end of the chromosome.
The extreme 5’ end of the lagging strand…
is not replicated.
The enzyme that extends telomeres is…
telomerase.
Telomerase binds to the…
3’ overhang of the telomere.
Telomerase uses … as a template
internal telomerase RNA
Telomerase extends the telomere by adding…
DNA nucleotides complementary to its internal RNA template.
After telomerase extends the 3’ overhang, … can bind, which extends…
DNA Polymerase α, an RNA primer to synthesize a complementary strand.
Approximately, … nucleotides need to be correctly inserted during DNA replication in a human diploid cell.
6 billion
DNA polymerases can make mistakes, leading to…
base mismatches.
Most replication errors are corrected by…
DNA polymerase itself.
The specific type of DNA polymerase that proofreads is…
DNA polymerase β.
DNA polymerase β has what type of activity for proofreading?
3’ to 5’ exonuclease activity.
After the mispaired nucleotide is removed, DNA polymerase…
fills the gap with the correct nucleotides.
The enzyme that seals the gap after error correction is…
DNA ligase.
The enzyme that relieves torsional strain ahead of the replication fork is…
topoisomerase.
Topoisomerase relieves torsional strain by…
breaking and rejoining DNA strands.
The enzyme that unwinds the DNA double helix at the replication fork is…
helicase.
Helicase unwinds DNA by…
breaking hydrogen bonds between the two strands.
The proteins that bind to single-stranded DNA and prevent it from reannealing are…
single-stranded binding proteins (SSBs).
The enzyme that synthesizes short RNA primers is…
primase.
Primase provides a starting point for…
DNA polymerase.
The main enzyme that adds nucleotides to the new DNA strand is…
DNA polymerase (δ and ε).
DNA polymerase (δ and ε) adds nucleotides in the … direction
5’ to 3’
The enzyme that extends the complementary strand from an RNA primer is…
DNA polymerase α.
DNA polymerase α helps solve…
the end of replication problem.
The enzyme that has a proofreading function is…
DNA polymerase β.
The enzyme that cleaves the RNA primer is…
exonuclease.
The enzyme that joins Okazaki fragments on the lagging strand is…
DNA ligase.
