W1-3 Comprehension Quiz Flashcards
Define Adenine
One of the 4 nitrogen bases associated with DNA. It is a purine that consists of 2 rings and matches with Thymine (AT) with 2 hydrogen bonds. It’s the weaker of the bases.
Define Allele
Different versions of a gene (normal or mutated)
Define Amino Acids
compounds found in living cells. Ex: oxygen, carbon, and hydrogen and nitrogent join together and form proteins.
Define Anneal
To attach. Example, primers anneal to DNA strands during PCR
Define Autosome
chromosomes 1-22 for humans. The non-sex chromosomes
Define Base Pairs
In the DNA structure, base pairs are AT or GC. Base pairs is how DNA is measured. (ex. 30 bps long means 30 base pairs). FUN FACT : It takes 10 base pairs to make a turn in the DNA double helix
Define Centromere
The “pinched” region along the chromosome that separates it into two arms. The can be located in the middle of the chromosome, or can be situated closer to the end of the chromosomes. The centromere is composed of a protein belt that functions as an attachment site for pulling two chromosomes apart during cell division
Define Condensed Chromosomes
DNA that has been tightly packed by condensin and resembles an X.
Define Condensin
The additional packing and coiling. A protein that helps DNA condense into chromosomes before the start of cell division.
Define Covalent Bond
A chemical bond that involves the sharing of electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs, and the stable balance of attractive and repulsive forces between atoms, when they share electrons, is known as covalent bonding.
Define Crossing Over
When chromosomes overlap, genetic material from one chromosome can trade places with genetic material from the other.
Define Cytosine
One of the 4 nitrogen bases associated with DNA. It is a pyrimidine that consists of 1 ring and matches with Guanine with 3 hydrogen bonds.
Define Denature
A process by which DNA double strands separate into single strands. This generally happens at very high temperatures.
Define Diploid
A cell with two chromosome copies.
Define Duplicated Chromosomes
The X-like structure that we commonly associate with chromosomes is actually a duplicated chromosome, where the chromosome has been copied and the two copies are held together at the centromere.
Define Exons
Remaining stretches of a DNA sequence that are spliced together and sent off to make proteins. They are the expressed parts. These sequences are called exons because they are the expressed sequence.
Define Expression
When a gene has been activated or turned on so its protein product is made.
Define Gametes
Sperm and Egg cells. A mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.
Gene
The short sequence of DNA that carries the sequence information to make the many proteins needed by the cell. It shows our traits
Guanine
One of the 4 nitrogen bases associated with DNA. It is a purine that consists of 2 rings and matches with Cytosine with 3 hydrogen bonds.
Haploid
A cell with only one set of chromosomes. An egg or a sperm is an example of a human haploid cell.
Define Helicase
The enzyme that unwinds and separates DNA during replication and creates replication forks.
Define Histone
The process of being tightly packed and folded
Define Homologous chromosomes
Non sex chromosomes
Define Hydrogen bond
The weaker of the two bonds. AT. The electrostatic attraction between polar groups that occurs when a hydrogen (H) atom bound to a highly electronegative atom such as nitrogen (N), oxygen (O) or fluorine (F) experiences attraction to some other nearby highly electronegative atom.
Define Introns
Long stretches of DNA that are removed before being read for protein manufacture. These sequences are called introns because they are the intervening sequence.
Define Ionic Bond
chemical bond that uses electrostatic attraction and interacts with ionic compounds.
between oppositely charged ions, and is the primary interaction occurring in ionic compounds. The ions are atoms that have lost one or more electrons (known as cations) and atoms that have gained one or more electrons (known as anions).
Define Karyotype
Used under a microscope to tell when the cell is in the process of dividing. A karyotype is the number and appearance of chromosomes in the nucleus of a eukaryotic cell. The term is also used for the complete set of chromosomes in an individual organism. Karyotypes describe the chromosome count of an organism and can be seen under a light microscope when the cell is in the process of dividing.
Define Lagging Strand
The lagging strand replicates in small segments called Okazaki fragments. These fragments are stretches of 100 to 200 nucleotides in humans (1000 to 2000 in bacteria) that are synthesized in the 5’ to 3’ direction away from the replication fork. Yet while each individual segment is replicated away from the replication fork, each subsequent Okazaki fragment is replicated more closely to the preceding replication fork than the fragment before. These fragments are then stitched together by DNA ligase, creating a continuous strand.
Define Leading Strand
The strand during DNA replication that is replicated from the 5’-3’ continuously.
Define Meiosis
The process of cell division in sexually reproducing organisms that reduces the number of chromosomes from diploid to haploid, as in the production of gametes.
Define Nucleic Acid
complex compounds found in living cells and viruses, made of purines (A,G) , pyrimidines (C,T) , carbohydrates, and phosphoric acid. Nucleic acids in the form of DNA and RNA control cellular function and heredity.
Define Nucleotide
they form the basic structural unit of nucleic acids such as DNA. a group of molecules that, when linked together, form the building blocks of DNA or RNA: in DNA the group comprises a phosphate group, the bases adenine, cytosine, guanine, and thymine, and a pentose sugar.a compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.
Define Okazaki fragments
Fragments on the Lagging Strand during DNA Replication because the DNA Polymerase can only add nucleotides from the 5’ end and this causes discontinuous fragments. This is one of the easiest ways to tell if this is a lagging strand instead of a leading strand.
Define Primase
Synthesizes RNA primer at the replication fork prior to DNA Polymerase.
Define Primer
A short strand of nucleotides that matches the DNA strand to be replicated.
Define Protein
A complex compound found in all living cells made of amino acids.
Define RNase H
Recognizes primers and removes them from DNA strand during DNA replication.
Define Random Alignment
This happens during metaphase I which allows equal opportunity for a particular chromosome to migrate into a cell.
Define Reagent
A substance used to detect, measure, examine, or produce other substances.
Define Recombinase
- An enzyme that encourages the exchange of short pieces of DNA between two long DNA strands, particularly the exchange of homologous regions between the paired maternal and paternal chromosomes during crossing-over.
Define Replication
The process by which cells copy DNA.
Define SSB protein
(Single strand binding protein) keeps the DNA strands separated during the replication process.
Define Satellite Regions
Stretches of DNA that exist between genes, or are found within a single gene between exons. often referred to as junk dna
Define Sex Chromosome
– The chromosomes that determine the gender of the species.
Define Sister Chromatids
- Two identical copies of a single replicated chromosome that are connected by a centromere.
Define Sliding Clamp
holds the polymerase to the DNA strand and increases processivity.
Define Telomeres
Highly repeated sequences. An enzyme that is able to build up additional TTAGGG repetitions at the end of each human chromosome and, thereby, counteract the shortening problem. When they get too short, they commit suicide. This enzyme is active in hair, skin and nail cells. Additionally it is active in embryonic cells, allowing newly conceived embryos a chance to regenerate their telomeres before starting development.
Define Tetrad
1 maternal and 1 paternal sister chromatid together. The first stage of meiosis is called prophase I, and this is when the tetrad forms. The two homologous chromosomes will align next to each other. But, since each is made up of two sister chromatids it will look like a group of four.
Define Thymine
One of the 4 nitrogen bases associated with DNA. It is a pyrimidine that consists of 1 ring and matches with Adenine with 2 hydrogen bonds.
Define Uncondensed Chromosomes
DNA that is spread throughout the nucleus. Spaghetti
Define Unduplicated Chromosomes
a single chromosome found in the nucleus during most of the lifetime of a cell. They look more like an “I”.
Define X Chromosome
In mammals, 2 copies of the X chromosome determine the female gender.
Define Y Chromosome
In mammals, it is the male gender determining chromosome.
Define Zygote
The fertilized egg produced by fusion of a male haploid gamete (in mammals, sperm) and a female haploid gamete (in mammals, egg).
Define DNA
DeoxyriboNucleic Acid
Explain DNA vs RNA
RNA has sugar ribose but DNA has sugar deoxyribose.
Define Chromatids
The Threads inside the nucleas
Define Nucleas
The structure in a cell that contains the genetic information
Name the 3 functional regions of DNA found in chromosome?
Genetic, Regulatory, and Satellite/Junk
What is a karyotype?
It is created by treated cells with a drug and it stops the cell division cycle. This helps to distinguish.
What does uncondensed DNA look like?
Spaghetti Noodles
What are Genes?
A Short sequences that carry the information from proteins. These proteins show the traits. Loss of protein also can reveal traits
What does condensed DNA look like?
It’s a chubby structure, perfect for travel.
What is the difference between Introns and Extrons?
Introns are the removed parts. Extrons are the expressed parts.
What is the SRY Gene?
It helps the Y chromosome act as a master switch for male development
What is the difference between DNA transcription and DNA translation?
When DNA is copied to RNA it is transcription, when RNA is used to produce proteins, its translation
How many chromosomes do most adults have? How many pairs?
46 chromsomes, 23 pairs.
Are chromatids and chromosome structure the same?
Yes but one is uncondensed and one is condensed.
Explain DNA vs. RNA
RNA contains the sugar ribose. DNA contains sugar deoxyribose. RNA has the base uracil while DNA has the base, thymine.
Explain Mitosis vs. Meoisis?
Mitosis is making identical cells for skin, hair, etc., Meiosis is creating genetic variety. Mitosis you divide once. In Meiosis you divide twice.
True or False We count centromeres by chromatids?
True
What does PMAT stand for?
Prophase, Metaphase, Anaphase, and Telaphase
Describe Prophase
This is when crossing over happen and genetic information is shared.
True or False: Mitosis is a cycle and it can happen many times
True!
Meosis Two cells start with a haploid or diploid number?
Haploid. These are gametes now and can then be used for fertilization. Sperm or egg cells.
What are Somatic cells?
They are non-sex cells.
Name the order of occurrence for events of Meiosis.
homologous chromosomes pair together
Crossover
Homologous chromosomes are randomly aligned along the center equator
Homologous chromosomes separate and go to opposite sides of the cell
Chromatids separate and go to opposite sides of the cell
Chromosomes are replicated.
What is synapsis?
the fusion of chromosome pairs at the start of meiosis.
What three things determine genetic identity?
Crossing over, random alignment, and random fertilization
What is cytoplasm?
A gel like fluid that is inside the cell
Name the four bases and the number of rings in its structure and the hydrogen bonds
Cytosine : one ring, 3 hydrogen bonds
Guanine : two rings and 3 hydrogen bonds
Adenine : two rings, 2 hydrogen bonds
Thymine : one ring and 2 hydrogen bonds
Why are GC pairs harder to pull apart than AT pairs?
Guanine and Cystine pairs have 3 hydrogen bonds where Adeline and thymine only have two. In result, the greater number hydrogen bonds, the harder it is to pull them apart.
If a DNA molecule has 18% Guanine, how much Cystosine, Adenine, and Thymine does it have?
Since we know that Guanine is 18% means that Cytosine always pairs with Guanine, so that would make it the same percentage as 36%. We need to find what percentages Adenine and Thymine are, so we subtract 36% from 100% = 64%. This means that together Adenine and Thymine are equal to 64%. When we divided 64 in half, that would be 32% for each. Adding them all up equals 100%.
Cytosine: 18%. Adenine: 32%, Thymine: 32%
What are the 3 parts a nucleotide is composed of?
A phosphate, a sugar, and a nitrogenous base.
Two strands of dna are anti-parallel meaning they u go along side each other but in opposite directions. T or f?
True
A double helix makes one complete turn every 50 nucleotides. True or false?
False. It’s ever 10 nucleotides.
Base pairs always have one purine and one pyramiding. T or F
True.
Covalent bonds are weak bonds and can be pulled apart. T or F
False. Hydrogen bonds are weak bonded. Covalent bonds do not break easily.
How many base pairs is in the human genome?
3.2 billion bp
What does PCR stand for and what does it mean?
Polymerase Chain Reaction, = synthesis of
DNA used with thermostable
equipment and polymerase in the
test tube, lab.
Define DNA Cloning
Prior to the 1980’s, the primary method for producing many copies of a gene
What is the key element of PCR?
Heat. DNA is submitting through heating and cooling cycles.
Explain the steps of PCR and how it works
Denaturation, Annealing, and Primer Extension. First, a small amount of DNA is gathered, a pair of primers are used to bind each end of the target sequence, Then a dna polymerase is used, then Four dNTPs (i.e., dATP, dCTP, dGTP, dTTP), and last a few essential ions and salts. They use those ingredients to to mimic the natural dna replication process. A thermocycler is used with cool and heat.
What is a Thermocycler?
A machine that jump-starts each stage of the reaction by raising and lowering the temperature of the chemical components at specific times and for a preset number of cycles.
What Denatursation? What temperature?
The melting of DNA into individual strands. 94 degrees.
What is Annealing? What temperature?
The reaction mixture is quickly cooled, usually between 30 and 65 degrees. This gives the primers an opportunity to bind or anneal to their complementary sequences on the single strands of DNA. 30-65 degrees.
What is Extension? What temp?
The sample is heated and the DNA polymerase begins to make a new DNA strand by attaching to the primers. 72 degrees.
What is (RT-PCR)?
Reverse Transcription Polymerase Chain Reaction, this combines real time PCR and reverse transcription.
What is Reverse Transcription?
The process that makes dna from rna
What is PCR used for?
Sequencing, cloning, forensics
What are the two primers called?
Forward and Reverse primers
What can we tell if both primers attach to the same piece of DNA and synthesize in the same direction?
That there is no PCR product
Explain the process of replication
Template strands separate, New nucleotides are added according to the templates, and they are joined into the new strand
T/F Replication happens during the G1 phase of the cell cycle
False. It happens during the S phase.
In the cell, splitting is performed by a protein called what
Helicase
What temperature does the helicase unwind the DNA helix at?
37 degrees which is body temperature
T/F Replication can occur in many directions
False. It can only occur in one direction
What is primase?
An enzyme consisting of RNA is added to a sequence, helps during the primer phase
What is a primer?
In the cell, a short primer sequence consisting of RNA is added
by a enzyme called Primase.
T/F Since the primer is actually made of RNA nucleotides, it must
be eventually removed and replaced with DNA.
True!
What are the five components required for PCR?
sample DNA, Primers, Polymerase, and the DnTp (which or can be At/GC’s). It also needs heat and cold, preferably a thermocycler.
What side does a primer need to bond onto DNA?
The 3 side, never the 5
If you start with 1 double-stranded DNA molecule as a template and
conduct a PCR for 5 thermal cycles, how many DNA molecules of the
PCR product will you synthesize at the end of the reaction?
If starting with 1 molecule, the final
number of double stranded DNA molecules
Calculated by (2) to the power of (# of thermocycles) x (# of copies)
T/F Amplification always occurs in the 5’ 3’ direction!!
True
Why do our cells require helicase, but we can get by without it
during PCR?
our cells need helicase over denaturazation because we can’t heat our bodies up to 94-95 degrees celsius without death but in a lab we have more flexibility and can speed up and manipulate that process.
