DNA Lecture 6 Flashcards
All the DNA that encodes the primary sequence of some final gene product (polypeptide or RNA with a structural or catalytic function)
Gene
A single large DNA molecule and its associated proteins, containing many genes. It stores and transmits genetic information
Chromosome
Although viral DNA molecules are small, the DNA molecules are much longer than the cells or viral packages in which they are found and vary greatly in size
Viruses
These contain much more DNA than viruses, they can have single double-stranded circular DNA molecules, and small circular molecules of DNA free in the cytosol called plasmids
Bacteria
These cells have even more DNA than prokaryotic cells, with DNA arranged into chromosomes. The amount of DNA per chromosome and the number of chromosomes is species dependent
Eukaryotic cells
Human cells have ____ times more DNA than an E. coli cell
The human body has a total DNA length of
700
2x10^11 km
more than 2x the circumference of the Earth
These cell types also have organelles, mitochondria, and chloroplasts than contain DNA.
In animal cells, mitochondrial DNA (mtDNA) is a
Eukaryotic cells
Circular Duplex
Genes and regulatory sequences make up almost all of the DNA in
Prokaryotes
Many ______ genes have a notable structural feature:
Their nucleotide sequences contain one or more intervening sequences of DNA that don’t code for the amino acid sequence of the polypeptide product
Eukaryotic
Non-translated DNA segments in eukaryotic genes are called intervening sequences, aka ____, and the coding segments are called ___
Introns
Exons
Cellular DNA is compact and highly organized, the folding into cells of DNA needs to pack it and permit access to the info in DNA.
This important property of DNA means the coiling of a coil, like a telephone cord coiling on itself
Supercoilng
DNA is coiled in the form of a
Addition coiling about the axis produces ____, it relieves that structural strain
Double helix
Supercoiling
When the is no net bending of the DNA axis onto itself, DNA is in
Relaxed State
Replication and transcription of DNA affect and are affected by ____
Both processes require, and helical intertwining complicates this.
supercoiling
Strand Separation
Does supercoiling occur in all cellular DNA?
Yes
The study of the properties of an object which don’t change under continuous deformations
Topology
In DNA, this term means conformational changes due to thermal motion or interaction with proteins or other molecules
Continuous Deformation
This means a DNA strand breakage
Discontinuous Deformations
Many naturally occurring DNA molecules, particularly bacteria but also DNA found in chloroplasts and mitochondria, are
Circular (no 5’ or 3’ end)
A circular DNA structure can be created by forming ____ bonds between the 5’ phosphate of one end and the 3’ OH of the other end of each strand of a linear DNA molecule
Phosphodiester
Plasmids and small viral DNAs are small circular DNAs. When they have no strand breaks, they are referred to as
Closed-Circular DNAs
Closed circular DNA that closely conforms to the B-DNA structure, 10.5 bp/turn, are said to be
Or, in their natural form, they are
relaxed
Supercoiled
DNA structure is strained, in a manner regulated by the cell, to induce
The strain is usually the result of _____ the DNA double helix in a closed circle.
supercoiling
Underwinding
In isolated closed, circular DNA, the strain is accommodated by supercoiling rather than strand separation because less energy is required to supercoil than to break
Hydrogen bonds
