UNIT 1 - A 1.2 - Nucleic Acids Flashcards
Information being passed down from one generation to another is in the form of what?
DNA
What does DNA stand for?
Deoxyribonucleic acid
Where do mutations occur?
Withing DNA
What are the four nitrogenous bases in DNA
adenine, thymine, cytosine, guanine
What are genetic messages/genes?
the sequences of nitrogenous bases
What are the genetic messages code for?
amino acids
What are amino acids known as?
The building blocks of proteins
What is the cell’s identity and function determined by?
the proteins it is able to synthesize
Why are viruses not considered alive?
Because they cannot survive without a cell of a living organism
When do viruses’s nucleic acid (RNA or DNA) become active?
When they infect a cell
What is the sole function of a virus
To reproduce itself
In the same order, what does the circle, pentagon, and rectangle represent in diagrams of nucleotides?
Phosphates, pentose sugars, and bases
What are both DNA and RNA considered?
polymers of nucleotides
What are polymers?
Repeating nucleotides within a larger molecule
What do nucleotides consist of?
One phosphate group, one five-carbon monosaccharide (pentose sugar), and a nitrogenous base
What kind of bonds occur at specific locations in order to produce a polymer?
Covalent bonds
How is a chain of nucleotides formed?
The pentose sugar of one nucleotide is covalently bonded to the phosphate group of the next nucleotide
What is found at the two ends of a nucleic acid polymer?
One phophate group with only one bond to a sugar at one end and a pentose sugar with only one bond to a single phosphate on the other end
Nucleotides bond to form a polymer as a result of what kind of reaction?
condensation reactions
Why are nucleic acid polymers made of nucleotides stable?
Because covalent bonds are relatively strong as they require quite a bit of energy to break
What are the four possible nitrogenous bases in RNA?
Adenine (A), Uracil (U), Cytosine (C), and Guanine (G)
What are the four possible nitrogenous bases in DNA?
Adenine (A), Thymine (T), Cytosine (C), and Guanine (G)
What pentose sugar does RNA contain?
Ribose
What pentose sugar does DNA contain?
Deoxyribose
How many different nucleotides are there in total?
8
When is RNA formed?
When nucleotides become bonded together in very specific sequences
How are nucleotides joined together?
Condensation reactions
What are condensation reactions between?
The pentose sugar of one nucleotide and the phosphate group of the next nucleotide
What do condensation reactions release?
A water molecule
What is the rule for determining the number of water molecules released during an RNA molecule’s synthesis?
The number of water molecules released is the same as the number of condensation reactions that took place which is one less than the number of nucleotides in the RNA molecule
What are the two strands/chains in DNA connected by?
Hydrogen bonds
What are the nitrogenous bases pairs in DNA?
Adenine (A) with thymine (T) and cytosine (C) with guanine (G)
What are complementary base pairs?
The nitrogenous base pairs: adenine with thymine and cytosine with guanine
Why are the two strands of DNA said to be antiparallel to each other?
Because the two strands are upside down in comparison to each other but parallel
What do all nucleotides of DNA consist of?
Deoxyribose sugar
What do all nucleotides of RNA consist of?
ribose sugar
What is the shape of DNA?
double helix
What acts as the permanent genetic code of a cell/organism?
DNA
What is the exception to RNA not containing a permanent genetic code?
RNA viruses
What is the molecular formula of ribose?
C5 H10 O5
What is the molecular formula for deoxyribose?
C5 H10 O4
What is the difference between ribose and deoxyribose according to their chemical formulas?
Deoxyribose has one less oxygen than ribose
What is an alcohol or hydroxyl group?
A -OH group bonded to a carbon
What do all living organisms use DNA as?
Their long-term hereditary storage molecule
What will not become useful to a cell if other nucleic acids are not at work?
The genetic information stored as genes in DNA
What are four other nucleic acids other than RNA and DNA?
Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Adenosine triphosphate (ATP)
What is an mRNA?
An RNA molecule synthesized from an area of DNA called a gene
Where does mRNA get its name as “messenger” RNA?
The mRNA leaves the nucleus of a cell and represents the genetic information necessary to make a protein
What are Transfer RNA?
special genes of DNA code for tRNA molecules
What is the function of a tRNA?
to transfer the correct amino acid into a growing chain of amino acids
What is RIbosomal RNA?
Same as tRNA: special genes of DNA code for rRNA
What is rRNA used to create?
an organelle in cells called ribosomes
What are ribosomes?
The cellular location where proteins are synthesized
What is Adenosine triphosphate (ATP)?
a single-nucleotide nucleic acid
What is ATP used in cells as?
A type of chemical energy
What is the ultimate purpose of cellular respiration?
To convert the energy contained within food molecules into the energy of ATP
What are the nitrogenous base complimentary pairing based on?
Hydrogen bonding
Why are the complementary base pairs the way they are?
A nitrogenous base can only form hydrogen bonds with its pair
Why are complementary base pairing important in DNA replication?
They allow exact copies of original DNA molecules to be able to be synthesized
Where does DNA store genetic information?
In its sequence of nitrogenous bases
What is a triplet codon?
Every three bases which represent a meaningful piece of information
What do many triplets within DNA code for?
one of the 20 amino acids
How many combinations of nucleotides are within the triplet code system?
64
What is the length of DNA limited by?
The amount that will fit efficiently into a cell
What is the shortest DNA molecule in the human genome?
about 50 million base pairs
What is the longest DNA molecule in the human genome?
About 260 million base pairs
From the knowledge we have about how long/how many nucleotides make up DNA molecules as well as all the different possible combinations, what can be concluded?
That DNA can contain a nearly limitless amount of genetic information
Why is the genetic code said to be universal?
Because all living organisms use the same genetic code
What percentage of gene sequence is the same in everyone?
99%
How does each person get their uniqueness?
From the 1% of remaining gene sequence
Why does one strand of a DNA molecule run 5’ to 3’ and the other strand run 3’ to 5’?
Because the two strands are antiparallel
Regardless of whether the top end is 5’ or 3’ in a DNA molecule, which direction do DNA strands always synthesize in?
From the 5’ nucleotide towards the 3’ nucleotide
What is the process of DNA replicating?
The two DNA strands speparate from each other in a particular area, and each separated strand acts as a template for a new strand to be formed
What are both DNA and RNA molecules integral to the process of?
protein synthesis
What is the first stage of protein synthesis called?
transcription
When does transcription occur?
When one strand of a DNA molecule is open and an RNA molecule is synthesized using complementary base pairing
What end of the RNA does the transcription process synthesize first?
The 5’ end
After the transcription process, what is the resulting RNA called?
mRNA
What does mRNA represent?
The genetic information of one gene
What organelle does the mRNA pair with?
Ribosome
What is the translation process?
tRNA, bonded to a specific amino acid, pairs to triplets of mRNA that had paired with ribosomes
Translation is accomplished in a sequence starting nearest to which end of the mRNA molecule?
The 5’ end
What are pyrimidines?
Thymine and Cytosine - single ringed structure
What are purines?
Adenine and Guanine - double ring structure
What makes the two strands of DNA maintain a consistant distance from each other?
A purine always bonds to a pyrimidine
What are histones
a type of protein in the nucleus of a cell
How do DNA molecules fit inside the nucleus of a cell?
DNA wraps itself around eight histones and one additional histone helps hold the structure together
What is a nucleosome?
The resulting structure of DNA ‘packaged’ around histones
What is linker DNA?
The DNA that extends from one nucleosome to the next
What is a chromosome?
The overall “packaged” shape after nucleosomes stack up and coil around other proteins in a condensed shape
How many chromosomes do human cells have?
46
What used to be debated as to what genetics was based on?
nucleic acids or proteins
What is a bacteriophage?
A virus that infects bacteria and is composed of a protein outer coat and an inner core of DNA
What two cultures were grown in the Hershey-Chase experiment?
One with radioactive phosphorus 32 and one with radioactive sulfur 35
How did Hershey and Chase end up proving that DNA, not protein, was the genetic material?
The two cultures of bacteriophages infected E.coli, radioactivity was detected inside the cells of the E.coli infected with the phosphorus 32 and not inside the cells of the E.coli infected with the sulfur 35. Because DNA contains phosophorus and not sulfur, it can be concluded that DNA is the genetic material.
What was the tetranucleotide theory?
That DNA existed in repeating sets of four nucleotides and was there to help give structure to chromosomes
What did the results of Chargaff’s research show?
Adenine and Thymine had the same ratio and Guanine and Cytosine the same ratio
What is Chargaff’s rule?
DNA contains the same number of adenine as thymine nucleotides, as well as the same number of guanine and cytosine nucleotides.
What was the importance of Chargaff’s rule?
It disproved the tetranucleotide theory as if it were true, there would be the same number of all four nitrogenous bases
