Lecture 1 review ( Molecular Genetics)

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Questions and Answers

Which region of the chromosome is designated as 'p'?

The centromere

The long chromosome arm

The short chromosome arm (correct)

The telomere

Which phase of the cell cycle does DNA replication occur?

S (correct)

What is the function of the G1 checkpoint control mechanism?

To ensure that everything is ready for DNA synthesis (correct)

To check if the cell is ready to complete cell division

To stop cell growth and focus on cell division

To ensure that everything is ready to enter the M phase

Which proteins control the cell cycle?

Cyclin-dependent protein kinases (Cdks) Signup and view all the answers

Which chromosome type has a centromere that is more central?

Metacentric Signup and view all the answers

What is the abbreviation for the resting phase where the cell has left the cycle and stopped dividing?

G0 Signup and view all the answers

Which checkpoint control mechanism ensures that everything is ready to enter the M (mitosis) phase and divide?

G2 checkpoint Signup and view all the answers

What is the abbreviation for the phase of the cell cycle where cell growth stops and cellular energy is focused on the orderly division into two daughter cells?

M Signup and view all the answers

Which chromosome type has a centromere that is less central?

Acrocentric Signup and view all the answers

Which region of the chromosome is designated as 'q'?

Long chromosome arms Signup and view all the answers

Which molecule carries the genetic information needed to specify all aspects of what makes a human being a functional organism?

DNA Signup and view all the answers

Where is the human genome found in the body?

In every nucleated cell Signup and view all the answers

What is the approximate number of genes in the human genome?

20,000 to 50,000 genes Signup and view all the answers

What are the components of nucleic acids?

Nitrogenous base, pentose, and phosphate Signup and view all the answers

How are the nucleic components of DNA held together?

N-glycosidic bonds Signup and view all the answers

Which nitrogenous base is found in both DNA and RNA?

Adenine Signup and view all the answers

Which molecule is composed of a nucleoside and one or more phosphate groups?

Nucleotide Signup and view all the answers

NTP is found in?

RNA Signup and view all the answers

An example of a di-nucleotide is

dNDP Signup and view all the answers

Which one of the following is NOT a function of nucleotides?

All the above are Signup and view all the answers

Which enzyme deficiency is associated with Hypouricemia?

Xanthine Oxidase Signup and view all the answers

Which enzyme deficiency is associated with Hyperuricemia in Lesch-Nyhan Syndrome/Juvenile Gout?

HGPRTase Signup and view all the answers

Which enzyme deficiency is associated with Severe Combined Immunodeficiency Diseases (SCID)?

Adenosine Deaminase Signup and view all the answers

What is the result of an immune system highly compromised in SCID?

Impaired function of both B cells and T cells Signup and view all the answers

match the sources of each required component of purine synthesis.

3 NH3 = 2 gln --> 2 glu carbon - = - N10 formyl THFA --> THFA carbon = CO2 3 NH3 - = - asp --> fumarate Signup and view all the answers

HGPRT is an enzyme used to change hypoxanthine into _ and Xanthine into _.

inosine; guanine Signup and view all the answers

In the purine degradation process, Inosine is catalyzed to hypoxanthine by?

phosphorylase Signup and view all the answers

The over expression of deaminase can cause?

Hemolytic anemia Signup and view all the answers

Sources of carbon and nitrogen for pyrimidine synthesis.

<h1>N-1,C-4, and C-6 = Aspartate C-2 = CO2 N-3 = amide N of glutamine</h1> Signup and view all the answers

Uracil is degraded to what during the degradation process of pyrimidines?

b-alanine Signup and view all the answers

Thymidine is degraded to what during the degradation process of pyrimidines?

beta - aminoisobutyrate and then urea Signup and view all the answers

What enzyme is used to synthesize deoxyribose from ribose

ribonucleotide reductase Signup and view all the answers

Thymidylate (dTMP) requires?

Folate and B12 Signup and view all the answers

Inhibitors of thymidylate synthesis that directly inhibit the dihydrofolate reductase (DHFR).

Methotrexate and Aminopterin Signup and view all the answers

Everything is true about pyrimidine synthesis except?

Need glycine to be synthesized. Signup and view all the answers

Inhibitor of thymidylate synthase.

5-fluorouracil (5-FU) Signup and view all the answers

chain growth is always to .

5'-3' Signup and view all the answers

A process to put nucleotide together is called?

polymerization Signup and view all the answers

What provides the monomers and energy needed for polymerization?

Triphosphate deoxyribonucleotide Signup and view all the answers

Define Bidirectional:

Both new strands synthesized simultaneously Signup and view all the answers

Prokaryotic polymerase that is considered the main processive replicative enzyme.

Pol III Signup and view all the answers

Replication enzyme functions

topoisomerase = cut the phosphate backbone SSB = Prevents single strands from rejoining DNA ligase = link okazaki fragments RNA primase = synthesizes RNA primer Signup and view all the answers

DNA polymerase roles in eukaryotic DNA synthesis.

alpha = Primer synthesis and repair gamma = mitochondrial DNA replication Delta = lagging strand synthesis and repair epsilon = leading strand synthesis and gap filling on lagging strand Signup and view all the answers

Exonucleases are defined as?

group of enzymes that remove nucleotide bases from the end of a DNA chain. Signup and view all the answers

All of these DNA synthesis inhibitors are considered chemotherapeutic agents except?

Aminopterin Signup and view all the answers

Karyotyping is usually done using chromosomes in what phase?

metaphase Signup and view all the answers

Euchromatin is the _ type of chromatin and predominantly found in cells during _.

active; interphase Signup and view all the answers

What reactions is considered the foundation of protein activation?

phosphorylation/dephosphoryation Signup and view all the answers

Telomeres serves as a termination zone.

True Signup and view all the answers

In humans, the sequence used as the "cap" is?

TTAGGG Signup and view all the answers

The erosion of the telomeres will affect the cell function

False Signup and view all the answers

Study Notes

Chromosome and Cell Cycle Basics

'p' designates the short arm of a chromosome.
DNA replication occurs in the S phase of the cell cycle.
The G1 checkpoint controls whether the cell is ready to proceed to DNA synthesis, assessing cell size and integrity.
Cyclins and cyclin-dependent kinases (CDKs) are pivotal proteins controlling the cell cycle.
Metacentric chromosomes have a centromere that is centrally located, while acrocentric chromosomes have a centromere that is near one end.

Cell Cycle Phases and Checkpoints

The resting phase where the cell has exited the cycle is abbreviated as G0.
The G2/M checkpoint ensures all is ready for the M phase and division.
The M phase focuses cellular energy on the orderly division into two daughter cells.

Genetic Information and Human Genome

'q' designates the long arm of a chromosome.
DNA carries genetic information essential for human function.
The human genome resides in the nuclei of cells.
The approximate number of genes in the human genome is around 20,000 to 25,000.

Nucleic Acids and Their Components

Nucleic acids consist of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.
The nucleotides in DNA are held together by phosphodiester bonds.
Adenine is a nitrogenous base found in both DNA and RNA.
Nucleotides, which are composed of a nucleoside and one or more phosphate groups, include NTPs.

Dipeptide nucleotides serve as an example of di-nucleotides.
The function that is NOT associated with nucleotides is their role as genetic information carriers.
Hypouricemia is linked to the deficiency of the enzyme xanthine oxidase.
Hyperuricemia in Lesch-Nyhan Syndrome and juvenile gout is due to a deficiency in hypo-xanthine guanine phosphoribosyltransferase (HGPRT).
Severe Combined Immunodeficiency Diseases (SCID) are associated with an adenosine deaminase deficiency, leading to a severely compromised immune system.

Purine and Pyrimidine Synthesis

HGPRT converts hypoxanthine to inosine monophosphate (IMP) and xanthine to uric acid.
In purine degradation, inosine is catalyzed to hypoxanthine by purine nucleoside phosphorylase.
Overexpression of deaminase can lead to toxic effects on cells.
Pyrimidine synthesis requires sources of carbon and nitrogen derived from aspartate and glutamine, respectively.
Uracil degrades to beta-alanine, while thymidine degrades to beta-aminoisobutyric acid (BAIB).

Enzyme Functions and Inhibitors

Thymidylate synthase enzymatically synthesizes deoxyribonucleotides.
Dihydrofolate reductase (DHFR) inhibitors block thymidylate synthesis.
Chain growth in nucleic acid synthesis follows the template direction.
The process of assembling nucleotides is termed DNA replication.
Monomers and energy for polymerization are provided by nucleotides and ATP.

DNA Synthesis and Chromatin Structure

Bidirectional replication refers to simultaneous synthesis of DNA in both directions from a replication origin.
DNA polymerase III is the primary prokaryotic enzyme for replicative processes.
Eukaryotic DNA polymerases also play key roles during DNA synthesis.
Exonucleases remove nucleotide residues from DNA, ensuring fidelity and correcting errors.
Karyotyping is typically performed on chromosomes in the metaphase stage.
Euchromatin is loosely packed chromatin, predominantly found in active cells.

Telomeres and Cellular Function

The "cap" sequence in humans used for telomere protection consists of repeated TTAGGG sequences.
Erosion of telomeres impacts cell longevity and function, leading to cellular aging and dysfunction.

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Test your knowledge on Thymidylate (dTMP) Synthesis Inhibitors in cancer therapy. Challenge yourself with questions on the role of B-12 and folate, one carbon metabolism, nucleoside analogs, and chemotherapeutic agents. Explore the inhibitors involved in Thymidylate Synthesis and their impact on cancer treatment.