Ch 3 Nucleic Acids Flashcards
What is responsible for most differences between organisms?
Gene variation
98.8% sequence identity
Where is DNA located in eukaryotic cells?
Nucleus
What is the structure of DNA in eukaryotes?
Linear and contained within chromosomes
How is DNA structured in prokaryotes?
Circular
What are genes composed of?
DNA
Do all genes coded by an organism’s DNA express as protein?
No, some code for functional RNA molecules
What are nucleic acids made of?
Polymers of nucleotides
What are the components of a nucleotide?
- A nitrogen base
- A monosaccharide (ribose)
- At least one phosphate
What distinguishes nucleosides from nucleotides?
Nucleosides consist of a nitrogen base and ribose sugar; nucleotides include a phosphate group.
What is the general structure of DNA?
A double helix
What type of bonds link nucleotides together?
Phosphodiester bonds
What does the central dogma explain?
How cells express genetic information
What are the three main processes involved in the central dogma?
- DNA replication
- Transcription
- Translation
What is the function of transcription?
RNA synthesis
What does translation produce?
Proteins
Which bases pair together in DNA?
- A pairs with T
- C pairs with G
What sugar is found in RNA?
Ribose
What sugar is found in DNA?
Deoxyribose
What are the components of chromatin?
- DNA
- Histones
What is supercoiling in DNA?
The three-dimensional arrangement of all atoms of DNA
What type of proteins are histones?
Positively charged proteins rich in lysine and arginine
What is a nucleosome?
A unit of DNA wound around histone proteins
What is the average length of the haploid human genome?
~3 billion nucleotides long
What is the structure formed by DNA wrapped around histones?
Chromatin
How do you read the sequence of bases in nucleic acids?
From 5′ to 3′
What is the significance of Rosalind Franklin in DNA research?
She contributed to the discovery of DNA’s structure through X-ray diffraction.
What is the difference between coding and noncoding portions of the genome?
Coding portions are translated into proteins; noncoding portions do not code for proteins.
What can a mutated gene cause?
Disease, such as sickle cell disease
True or False: DNA contains thymine while RNA contains uracil.
True
Fill in the blank: The sugar atoms in nucleotides are numbered with _______ to distinguish them from the attached bases.
primes
What is the role of coenzyme A?
Capturing free energy
What are the three structural forms of DNA?
- B-DNA
- A-DNA
- Z-DNA
What is the arrangement of all atoms of the DNA called?
Supercoiling
Supercoiling refers to the overwinding or underwinding of the DNA strand.
What proteins are involved in the supercoiling of eukaryotic DNA?
Histones
Histones are positively charged proteins that help package DNA into chromatin.
What are histones rich in?
Basic amino acids Lys and Arg
These amino acids contribute to the positive charge of histones.
What is chromatin?
A complex of DNA wound around histones in a bead-like structure
Chromatin plays a crucial role in DNA packaging and regulation.
What is the structure of chromatin often described as?
Beads on a string
This description refers to the nucleosome structure formed by DNA wrapped around histones.
What is each ‘bead’ in the chromatin structure called?
Nucleosome
Nucleosomes are the fundamental units of chromatin.
What does the stability of a DNA double helix depend mostly on?
Stacking interactions
Stacking interactions refer to the interactions between adjacent base pairs in the DNA strand.
True or False: DNA can denature (unfold).
True
Denaturation refers to the separation of the two strands of DNA.
True or False: DNA can renature (refold, anneal).
True
Renaturation is the process where separated DNA strands rejoin.
