Quiz unit 3 Flashcards
This is a molecule found in the nucleus that carries the genetic material.
Chromosome
The chromosome is made up of ______________ chromatids attached at a point called the ___________.
two identical sister
Centromere
The centromere divides the chromosomes into two sections called ________
Arms
The shorter arm of the chromosome is referred to as the _________
p arm
The longer arm of the chromosome is referred to as the ________
q arm
What are the four types of chromosomes based on the location of the centromere?
- Telocentric chromosome
- Acrocentric chromosome
- Submetacentric chromosome
- Metacentric chromosome
It is a type of chromosome where the centromere is located at the tips of the chromosome.
Telocentric chromosome
An ___________ has centromeres located quite near the tip of the chromosome.
Acrocentric chromosome
____________ have a centromere located near the middle, resulting in a slightly unequal arm.
Submetacentric chromosomes
The _____________ has a centrally located centromere with p and q arms of almost the same length.
Metacentric chromosome
The compact arrangement of the chromosome is visible only during _____ or ______ of the cell cycle.
cell division or the M-phase (also known as mitosis)
During __________, the chromosome is a loosely arranged chromatin.
interphase
A single chromosome is made up of a ______ DNA molecule __________ by proteins called _______.
single;
supercoiled;
histones
A DNA molecule is made up of _____ DNA strands arranged in an _________ and twisted into a _______
Two;
antiparallel manner;
double helix
DNA is made of two strands. Each strand is made up of what three components?
Phosphate Group
Sugar Group
Nitrogenous Bases
A sugar and a nitrogenous base form a ________
Nucleoside
What is the function of the phosphate groups in DNA synthesis?
Phosphate groups contain high-energy bonds, which bind one nucleoside with an adjacent nucleoside. Forming an entire strand of DNA.
In sugar groups, the type of sugar in DNA is called a ________
5-carbon ring of deoxyribose sugar
In a nucleotide, the sugar is attached to the phosphate by its __________ carbon .
5’ carbon
What is a nitrogenous base?
It is an organic molecule made up of nitrogen
How can nitrogen become a base?
Its two lone electrons can act as a base in chemical reactions.
What are the two types of nitrogenous bases and their subtypes?
Purines: Adenine and Guanine
Pyrimidines: Cytosine and Thymine
Purines and pyrimidines form ____________ attached by what type of bonds?
Complementary base pairs; Hydrogen bonds.
Adenine always pairs with ________, forming how many hydrogen bonds?
Thymine; 2 hydrogen bonds
Guanine always pairs with_______ forming how many bonds?
Cytosine: 3 hydrogen bonds
In the arrangement of the nucleotide in each DNA strand. The _____________ forms the “backbone” of each strand while the ___________ form hydrogen bonds to bind the two strands together and form an entire DNA molecule
Phosphate-sugar combination (or phosphate and sugar groups)
nitrogenous bases
Group of proteins responsible for DNA packaging
Histones
What are the four types of histone proteins?
H2A, H2B, H3, H4
In histones, The DNA strand is wound around the ______ during the _______
octamer; initial DNA packaging
This protein is responsible for the second level of DNA packaging
Histone 1
There are _______ and ______ proteins that are responsible for packaging the DNA so that it would fit into the tiny nucleus and still be functional.
histone and non-histone
The first level of packaging is the formation of the ___________
Nucleosome
Histones 3 (H3) and histones 4 (H4) proteins allow the 2 nm diameter DNA to wind around the _____ once, forming a ______
Tetramer; Tetrasome
A more reliable packaging is achieved if histones ____ and _____ are also present, allowing the DNA to form a negative superhelical (counterclockwise) turn around a histone octamer twice, forming the _____
2A and 2B; Nucleosome
A series of nucleosomes form the _______ that looks like “_________”
chromatin; beads on a string
What are two models proposed regarding the possible configuration of chromatin?
Zigzag and solenoid
The third level of compaction is formed by the interaction between the 30 nm fiber and the nuclear matrix; forming 300 nm radial loops called the ________.
euchromatin
The ____________ of the 30 nm fiber anchor to the nuclear matrix via internal matrix proteins, forming what shape?
matrix attachment regions (MARs); loop
Although compact, the ______ of the euchromatin still allows _______to access the DNA during the transcription phase of protein synthesis
radial loops; transcription factors
Further compaction of the 300 nm euchromatin forms a ____ nm _________
700nm; heterochromatin
This level is a tightly compacted chromatin region that prevents transcription factors from accessing the DNA. Thus, no transcription occurs in __________ segments
Heterochromatin
There are two types of heterochromatin;
Constitutive and Facultative
Permanently inactive heterochromatin - formed by DNA segments that are no longer used or needed by the cell
Constitutive heterochromatin
Inactive for some time, then uncoils back to euchromatin if the transcription is required by the cell, then coils again into heterochromatin - formed by DNA segments that are still used or needed by the cell
Facultative Heterochromatin
During the ______ stage of cell division, the chromatin enters the last level of compaction
prophase
In the prophase stage, all euchromatin coils into heterochromatin, then all heterochromatin undergoes ______ to form the chromosome
Supercoiling
Two types of structural maintenance chromosome (SMC) proteins participate in anchoring the chromatin as it forms the chromosome. Which are?
Cohesins and Condensins
Shortly before prophase, __________ bind sister chromatids together along their entire length and remain in position until the chromosome is formed.
Cohesins
As the cohesins hold on to the sister chromatids, the condensins aid in the _____________ until the final metaphase chromosome is formed
coiling of the chromatin
Shortly before _______, the cohesins detach, separating the arms of the chromosome but remains attached in the constricted region called the centromere
metaphase
Shortly before ________, cohesins bind sister chromatids together along their entire length and remain in position until the chromosome is formed
prophase
State the levels of compaction along with their expected measurements respectively.
- DNA double-helix (2nm)
- Nucleosome (11 nm)
- Chromatin (30nm)
- Euchromatin (300nm)
- Heterochromatin (700nm)
- Chromosome (14000nm)
What type of bond connects nitrogenous bases?
Hydrogen bonds
What do phosphodiester bonds connect within the DNA structure?
Adjacent sugar groups
What do esther bonds connect within the DNA structure?
Phosphate and sugar groups
What do N-glycosidic bonds connect within the DNA structure?
Sugar groups and nitrogenous bases.
Why are the two strands of DNA anti-parallel to each other?
It allows FAITHFUL REPLICATION. It ensures the production of identical genetic materials.
How many human DNA are there?
46 DNAs
This term refers to the abundance of Thymine and Adenine nucleic acids.
Tatabox
What constitutes Chromatin?
DNA plus Proteins
This type of DNA groove allow proteins to bind to and recognize DNA sequences from the outside of the helix.
Major groove
Which of the four types of chromosomes (based on centromere position) is not found in humans?
Telocentric Chromosomes.
