DNA Structure Flashcards
Genes are made up of a long molecule called ___
DNA
is made up of simple units that line up in a particular order within its large molecule
DNA
language used by DNA is called
geentic code
is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms
deoxyribonucleic acid
draw DNA structure
+1
main role of DNA
long term storage of information
DNA is used to construct other components of cells such as
proteins
RNA
DNA segments that carry genetic information are called
genes
other DNA sequences that do not carry genetic information have what purposes
structural purposes
regulate use of genetic information
DNA cosnsist of two long polyemers of simple units called
nucleotides
DNA backbone is made up of ___ and ___
sugars and phosphate groups
bond joining sugar and phosphate group in DNA
phosphodiester bond
two strands run in opposite directions to each other and are therefore ____
anti-parallel
attached to each sugar is one of the four types of molecules called ___
bases
the structure of DNA was first discovered by ___ and ___
James D. Watson
Francis Crick
size of DNA strand (pitch and radius)
34 angstroms (3.4 nanometers)
10 angstroms (1.0 nanometers)
what are the three components that make up a nucleotide?
phosphate group
pentose sugar
nitrogenous base
- This provides the molecule’s acidic properties and participates in linking nucleotides together to form long chains.
phosphate group
A five-carbon sugar, which is either ribose (in RNA) or deoxyribose (in DNA), distinguishes the two types of nucleic acids.
pentose sugar
pentose sugar can be:
ribose (in RNA) or deoxyribose (in DNA)
A nitrogen-containing molecule that comes in four types: adenine (A), guanine (G), cytosine (C), and thymine (T) in DNA, or uracil (U) replacing thymine in RNA.
nitrogenous base
nitrogenous bases in DNA are
adenine (A), guanine (G), cytosine (C), and thymine (T)
nitrogenous base in RNA
adenine (A), guanine (G), cytosine (C), and uracil (U)
the “backbone” of the DNA molecule is made up of two alternating components, what are these?
deoxyribose sugar
phosphate group
there are four different variations of these monomers (four different bases), what are the names of those bases
adenine
thymine
cytosine
guanine
what are the chemical bonds that connect each of the component in DNA?
phosphodiester bond
hydrogen bond
glycosidic bond
These connect the phosphate group of one nucleotide to the sugar of the next, creating the sugar-phosphate backbone of the DNA strand.
phosphodiester bond
These hold the complementary nitrogenous bases (A pairs with T; G pairs with C) together between the two strands of the DNA double helix.
hydrogen bond
These connect the nitrogenous base to the sugar molecule in each nucleotide.
glycosidic bond
specific base pairing of nitrogenous bases
adenine - thymine
guanine - cytosine
the bases are paired by ___ bonds along the axis of the molecule
hydrogen bonds
write the complementary sequence of the DNA strand:
3’ A T C G T A A C G T G C A 5’
5’ T A G C A T T G C A C G T 3’
approximate distance between each base pairs
0.34 nm
if the dsDNA is 2.5 mm long, and is composed of 15% adenine, how many cytosine bases are present in given DNA
5.145
×
10
6
cytosinebases
in mammals 40% of the DNA is composed of G-C base pairs, in thermophilic bacteria, the G-C content is 74% or higher. Why is a high G-C content advantageous for a bacterium living in hot spring or vents?
The advantage of a high G-C content in thermophilic bacteria is due to the three hydrogen bonds that form between guanine (G) and cytosine (C), as opposed to the two hydrogen bonds that form between adenine (A) and thymine (T). These extra hydrogen bonds provide greater stability to the DNA double helix, making it more resistant to the high temperatures of hot springs or thermal vents. In contrast, DNA with higher A-T content is less stable at elevated temperatures.
in mammals 40% of the DNA is composed of G-C base pairs, in thermophilic bacteria, the G-C content is 74% or higher.
how many adenine bases are present in mammals? thermophilic bacteria?
If 40% of the DNA in mammals is composed of G-C base pairs, then the remaining 60% consists of A-T base pairs. Since adenine (A) and thymine (T) are present in equal amounts, adenine constitutes 30% of the total DNA bases in mammals.
For thermophilic bacteria, 74% of the DNA is G-C base pairs, leaving 26% for A-T pairs. Thus, adenine constitutes 13% of the total DNA bases in thermophilic bacteria (as A and T are equal).
Established by James Watson
and Francis Crick (1950’s)
DNA
contains the instructions for
making proteins within the cell.
DNA
shape of DNA
double helix
repeating subunits of DNA
nucleotides
X-ray diffraction patterns produced by DNA fibers are done by
Rosalind Franklin and Maurice Wilkins
played a pivotal role in uncovering the structure of DNA. Her expertise in X-ray diffraction led to the creation of the famous “Photo 51,” which revealed the double-helix structure of DNA
Rosalind Franklin
was instrumental in the discovery of DNA’s double-helix structure. He conducted X-ray diffraction studies on DNA fibers, which provided key data for James Watson and Francis Crick’s model. Wilkins worked at King’s College London, where he collaborated with Rosalind Franklin, although their relationship was strained due to misunderstandings about their roles.
Maurice Wilkins
how important is xray diffraction patterns in discovering the structure of DNA
X-ray diffraction patterns were absolutely essential in discovering DNA’s structure. These patterns provided direct evidence about the arrangement of atoms within the DNA molecule. Rosalind Franklin’s “Photo 51” was particularly critical—it revealed the helical nature of DNA and gave clues about its dimensions, including the distance between bases and the regularity of the helix.
is a tool used to provide structural information about molecules.
xray crystallography
determines the atomic and molecular structure of a crystal by analyzing how X-rays diffract (scatter) when passing through it, revealing the arrangement of atoms within the crystal.
xray crystallography
most common DNA structure
B DNA
pyrimidines include
thymine
cytosine
purines include
adenine
guanine
three representations of DNa
ribbon moddel
partial checmical structure
computer model
representation of DNA that shows its helical shape
ribbon model
representation of DNA that shows bonds and structures of sugar phosphate backbone
partial chemical structure
representation of DNA that is used in simulation activity when studying interactive models
shows preside atom position as well as molecular movement
essential for research
computer model
model of DNA that is translated to code by IT to make a model to predict what will happen given a condition
numerical modelling
structural forms of DNA
A DNA
B DNA
Z DNA
structural form of DNA that is right handed, the model where Watson and Crick has shown
B DNA
common form of DNA in nature, classic, long an thin
B DNA
right handed helix, wider and short
A DNA
DNA that is dehydrated/hybrid RNA-DNA samples
A-DNA
Right-handed helix with 11 base pairs per turn.
A DNA
Right-handed helix with 10 base pairs per turn.
B DNA
left handed double helix
Z DNA
less common structural form of DNA, associated with alternate, involved gene regulation
Z DNA
Has 12 base pairs per turn, and the bases are in a zigzag conformation rather than being neatly aligned.
Z DNA
Slimmer and more elongated than B-DNA, with a zigzag pattern in its sugar-phosphate backbone, which gives Z-DNA its name.
Z DNA
orms under specific conditions, such as high salt concentrations, supercoiling stress, or sequences rich in alternating purines and pyrimidines (like CG repeats).
Z DNA
Found in the nucleus of eukaryotic cells, Organized into multiple linear chromosomes, which are wrapped around histones to form chromatin.
genomic DNA
Found in the mitochondria, which are the energy-producing organelles.
Circular and much smaller than genomic DNA, resembling bacterial genomes (a relic of their evolutionary origin from prokaryotes).
mitochondrial DNA
Passed down maternally in most organisms, meaning it is inherited solely from the mother.
mitochondrial DNA
Contains a small set of genes primarily involved in oxidative phosphorylation and encoding tRNAs and rRNAs.
mitochondrial DNA
a form of synthetic DNA generated from messenger RNA (mRNA) through a process called reverse transcription
complementary DNA
form of DNA used in labs from mRNA, used in molecular biology
complementary DNA
is the synthesis direction of the template strand during DNA replication or transcription
3’ to 5’
it’s important to clarify that the actual synthesis of new DNA or RNA strands occurs in the
5’ to 3’
The complementary strand of DNA is synthesized in what direction
5’ to 3’
connects the sugar to the
nitrogen base.
beta n-glycosidic bond
__hydrogen bonds
between C and G;
three
-___hydrogen bonds
between A and Т.
two
These rules helped to determine and established the pattern of nitrogenous base pairing in DNA
Chargaff’s rules
Ratios of nucleotides
chargaff’s rules
- A+T does/does nothave to equal G+C
does not
which base pair is stronger and more stable
guanine and cytosine
Two strands of DNA form a
___
right-handed double helix.
- There are ~___ nucleotides in each
strand per complete 360° turm of
the helix.
10 nucleotides
one turn of DNA is composed of ___ base pairs
10
10 base pairs is equal to ___ angstron or __ nanometer
34 angstrom
3.4 nm
1 base pair is equal to ___ angstrom or ___ nanometer
3.4 angstrom
0.34 nanometer
angstrom to nanometer conversion
1 angstrom = 0.1 nm
diameter of DNA (angstrom and nm)
20 angstrom (2 nm)
radius of DNA
10 angstrom (1 nm)
DNA was extracted from cells of
Staphylococcus and found to have 37%
cytosine. What percent of guanine does
this species have?
37%
What percent of thymine does this
species have?
13%
conversion factor of mm to nm
1 mm = 1,000,000 nm
helix of
A DNA
B DNA
Z DNA
right
right
left
base pairs per turn of:
A DNA
B DNA
Z DNA
~11
~10.5 or 10
~12
helical diameter of
A DNA
B DNA
Z DNA
2.6
2.0
1.8
helical length of
A DNA
B DNA
Z DNA
2.6
3.4
3.7
shape of
A DNA
B DNA
Z DNA
broadest
intermediate
narrowest
major groove of
A DNA
B DNA
Z DNA
wide, deep
narrow, deep
flat
minor groove of
A DNA
B DNA
Z DNA
narrow, shallow
broad, shallow
narrow, deep
22 pairs of chromosome are called
autosome
shape of prokaryotic DNA
circular
is complexity equal to size?
no
variation in euakryotes is due to
non coding DNA
A segment of DNA that codes for a
protein, which in turn codes for a trait (skin
tone, eye color…etc.), a gene is a stretch of
DNA.
Gene
is certain region of DNA
which is converted during a proces
called transcription
gene
A gene is certain region of DNA
which is converted during a proces
called
transcription
A gene is certain region of DNA
which is converted during a proces
called
transcription
A gene is certain region of DNA
which is converted during a proces
called transcription into an
intermediate sequence of chemical
distinct nucleotides called an
RNA
In a process called
___, RNA is then used to
produce proteins that can be used
the cell to maintain its activity
translation
The
entire process is sometimes called
the “-____ ___“of molecular
biology.
central dogmage
genes carry genetic information for different functions such as
fundamental for heredity
blueprint for molecules
working units of DNA
