Untitled Flashcards Set

What is transcription in molecular biology?

Transcription is the process of using parts of the DNA sequence as a template to synthesize RNA.

What are the main types of RNA involved in cellular processes?

rRNA, tRNA, snRNA, and mRNA.

What is the role of the promoter in transcription?

A promoter is a specific DNA sequence where transcription starts, determining which DNA strand is read and how many RNA copies are made.

What is the main enzyme involved in RNA synthesis?

RNA polymerase is the main enzyme that synthesizes RNA.

Describe the process of RNA processing in eukaryotes.

Primary transcripts must be processed to add a 7mG cap, a poly-A tail, and undergo splicing to remove introns.

What is the difference between the leading strand and the lagging strand in DNA replication?

The leading strand is synthesized continuously while the lagging strand is synthesized in fragments known as Okazaki fragments.

What is the role of DNA polymerase in replication?

DNA polymerase adds nucleotides to the growing DNA strand and has proofreading activity to correct errors.

What are telomeres and why are they important?

Telomeres are repetitive DNA sequences at the ends of chromosomes that protect DNA from degradation during replication.

What is translation in the context of molecular biology?

Translation is the process by which ribosomes use mRNA to synthesize proteins.

What signals the beginning of translation?

The start codon, which is usually AUG, signals the beginning of translation.

Where does translation occur in the cell?

Translation occurs in the cytoplasm on free ribosomes or rough endoplasmic reticulum (ER).

What is the function of chaperones in protein synthesis?

Chaperones assist in the proper folding of proteins to ensure they achieve their functional structure.

How do electron transport chain (ETC) and photosynthesis compare in terms of electron donors?

In the ETC, NADH and FADH₂ act as electron donors; in photosynthesis, water (H₂O) is the electron donor.

What is mismatch repair in DNA repair mechanisms?

Mismatch repair fixes mistakes made by DNA polymerase immediately after replication.

What distinguishes acidic amino acids from basic amino acids?

Acidic amino acids lose an H⁺ at physiological pH, resulting in a negatively charged side chain; basic amino acids gain an H⁺, resulting in a positively charged side chain.

How do cancer cells utilize nanotubes in relation to mitochondria?

Cancer cells use nanotubes to hijack mitochondria from immune cells, enhancing their metabolic processes.

What is the characteristic structure of microtubules?

Microtubules are larger, hollow tubes composed of tubulin that exhibit dynamic instability.

What is the role of microfilaments in the cell?

Microfilaments are involved in cell movement, shape, and muscle contraction, and are composed of actin.

What are the key differences between microtubules and microfilaments?

Microtubules are larger, hollow tubes composed of tubulin and are involved in cell structure and transport; microfilaments are thinner, composed of actin, and are involved in cell movement and contraction.

What is mismatch repair in DNA replication?

Mismatch repair occurs immediately after DNA replication, detecting and correcting mismatched base pairs by removing the erroneous DNA segment and resynthesizing the correct sequence.

What is base excision repair?

Base excision repair fixes single base lesions, such as those caused by deamination, and occurs throughout the cell cycle independent of DNA replication.

What is nucleotide excision repair?

Nucleotide excision repair removes bulky DNA lesions, like thymine dimers from UV light exposure, by excising the damaged DNA segment and filling the gap with the correct nucleotides.

What are the electron donors in the Electron Transport Chain?

NADH and FADH₂ are the electron donors produced during glycolysis, pyruvate processing, and the TCA cycle.

What is the final electron acceptor in the Electron Transport Chain?

Oxygen (O₂) acts as the final electron acceptor, combining with electrons to form water (H₂O).

How is the proton gradient formed in the Electron Transport Chain?

Electrons are passed through protein complexes in the inner mitochondrial membrane, which pumps protons (H⁺) into the intermembrane space, creating a proton gradient.

What is the role of ATP synthase in the Electron Transport Chain?

ATP synthase utilizes the proton gradient to drive the synthesis of ATP.

What are the electron donors in photosynthesis?

Water (H₂O) is the electron donor in photosynthesis, which is split to release oxygen (O₂).

What is the final electron acceptor in photosynthesis?

NADP⁺ is the final electron acceptor in photosynthesis, reduced to NADPH.

How is the proton gradient formed in photosynthesis?

Protons are pumped across the thylakoid membrane during the light reactions, creating a proton gradient.

What is the role of ATP synthase in photosynthesis?

ATP synthase uses the proton gradient created in the thylakoid membrane to generate ATP.

What is the Calvin Cycle and its relationship to photosynthesis?

The Calvin Cycle uses the ATP and NADPH produced in the light reactions to convert carbon dioxide (CO₂) into glucose.

What is the start codon in mRNA?

The start codon is the first codon in mRNA that signals the start of translation, coding for the amino acid methionine (AUG).

How do eukaryotic and prokaryotic mRNAs differ in their translation initiation?

Eukaryotic mRNAs are monocistronic (one mRNA codes for one protein) and start at the first AUG; prokaryotic mRNAs are polycistronic (one mRNA codes for multiple proteins) and can begin translation at multiple AUGs, each preceded by a Shine-Dalgarno sequence.

What are the functions of ribosomes in translation?

Ribosomes are molecular machines that facilitate protein synthesis by binding mRNA and tRNA, consisting of large and small subunits.

What role do tRNAs play in translation?

tRNAs transfer specific amino acids to the ribosome during translation, carrying an anticodon that pairs with the mRNA codon.

What are initiation, elongation, and release factors?

They are proteins that facilitate the different stages of translation: initiation (start process), elongation (adding amino acids), and termination (releasing the protein).

How many different amino acids are involved in protein synthesis?

There are 20 different amino acids, each with a unique side chain (R group).

What occurs during the initiation stage of translation?

During initiation, the ribosome assembles around the mRNA, and the first tRNA carrying methionine binds to the start codon.

Describe the elongation step of translation.

In elongation, the ribosome moves along the mRNA, matching each codon with the appropriate tRNA and catalyzing peptide bond formation between amino acids.

What happens during the termination of translation?

During termination, when a stop codon is reached, release factors cause the ribosome to dissociate, releasing the newly synthesized protein.

Why is proper protein folding important?

Proper protein folding is essential for function; misfolded proteins are assisted by chaperones or degraded by the proteasome if unrepaired.

What is DNA replication?

DNA replication is the process of copying the entire DNA sequence to ensure that both daughter cells receive identical genetic information during cell division.

What are origins of replication?

Origins of replication are specific DNA sequences where replication begins, allowing for multiple replication forks to form in eukaryotic chromosomes.

What is the leading strand in DNA replication?

The leading strand is synthesized continuously in the 5’ to 3’ direction.

What is the lagging strand in DNA replication?

The lagging strand is synthesized discontinuously as Okazaki fragments in the 5’ to 3’ direction but overall replication is 3’ to 5’ relative to the template.

What is the role of DNA polymerase?

DNA polymerase adds nucleotides to the growing DNA strand and ensures base-pairing with the template strand.

What is the function of helicase in DNA replication?

Helicase unwinds the DNA double helix ahead of the replication fork.

What is the purpose of sliding clamp proteins?

Sliding clamp proteins help hold DNA polymerase onto the DNA template during replication.

What do single-strand binding proteins (SSBPs) do?

SSBPs bind to and stabilize single-stranded DNA to prevent reannealing or degradation.

How do DNA ligase function in the process of replication?

DNA ligase joins Okazaki fragments on the lagging strand by sealing the sugar-phosphate backbone.

What are deoxyribonucleotides?

Deoxyribonucleotides are the building blocks of DNA, consisting of Adenine (A), Cytosine (C), Guanine (G), and Thymine (T).

What is proofreading in DNA replication?

Proofreading is the process by which DNA polymerase corrects errors during replication using its 3’ to 5’ exonuclease activity.

What is mismatch repair?

Mismatch repair is a mechanism that fixes errors not corrected by proofreading, occurring immediately after replication by removing and replacing incorrect bases.

What are telomeres?

Telomeres are repetitive DNA sequences at the ends of chromosomes that protect DNA from degradation during replication.

What is the role of telomerase?

Telomerase is an enzyme that extends telomeres by adding repetitive nucleotide

What is transcription?

Transcription is the process in which a segment of DNA is used as a template to synthesize RNA.

What are the types of RNA synthesized during transcription?

Types of RNA include rRNA (ribosomal RNA), tRNA (transfer RNA), snRNA (small nuclear RNA), and mRNA (messenger RNA).

What role does rRNA play?

rRNA is part of the structure of ribosomes and is crucial for protein synthesis.

What is the function of tRNA?

tRNA carries amino acids to the ribosome for protein synthesis.

What is snRNA involved in?

snRNA is involved in splicing pre-mRNA.

What is the role of mRNA?

mRNA carries the genetic code from DNA to the ribosome for protein synthesis.

What is the promoter in transcription?

A promoter is a specific DNA sequence where RNA polymerase binds to initiate transcription.

How do core promoters and enhancers affect transcription?

Core promoters and enhancers modulate the rate of transcription.

What is the main enzyme involved in transcription?

RNA polymerase is the enzyme that synthesizes RNA by adding ribonucleotides complementary to the DNA template.

What are general transcription factors?

General transcription factors are required by all promoters to initiate transcription and assist in RNA polymerase recruitment.

What are transcriptional activators?

Transcriptional activators are proteins that bind to specific DNA regions (enhancers) to increase the transcription rate of particular genes.

What are ribonucleotides?

Ribonucleotides are the building blocks of RNA; they include Adenine (A), Cytosine (C), Guanine (G), and Uracil (U).

In what direction is RNA synthesized?

RNA is synthesized in the 5’ to 3’ direction.

What is the purpose of the 7-methylguanosine (7mG) cap?

It protects the RNA from degradation and helps with ribosome binding during translation.

What is a Poly-A tail and its function?

The Poly-A tail increases stability and aids in the nuclear export of mRNA.

What is splicing?

Splicing is the process of removing introns and joining exons in pre-mRNA.

What is alternative splicing?

Alternative splicing allows one gene to code for multiple proteins by varying the included exons in

What is mitosis?

Mitosis is the process by which a eukaryotic cell divides to produce two genetically identical daughter cells.

What are the key features of mitosis?

Mitosis aims to produce two daughter cells that are genetically identical, maintaining the same chromosome number as the parent cell.

In what type of cells does mitosis occur?

Mitosis occurs in somatic (body) cells.

What are the phases of mitosis?

Mitosis consists of Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

What takes place during interphase in preparation for mitosis?

Interphase includes G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis).

What occurs in prophase?

In prophase, chromosomes condense and become visible, the nuclear membrane begins to break down, and the mitotic spindle starts to form.

What happens during metaphase?

In metaphase, chromosomes line up along the metaphase plate, and spindle fibers attach to their centromeres.

What occurs in anaphase?

During anaphase, sister chromatids are pulled apart by spindle fibers toward opposite poles of the cell.

What happens in telophase?

In telophase, chromosomes de-condense into chromatin, nuclear membranes re-form around each set of chromosomes, and spindle fibers disassemble.

What is cytokinesis?

Cytokinesis is the final step in cell division where the cytoplasm divides, resulting in two distinct daughter cells.

What is meiosis?

Meiosis is a type of cell division that reduces the chromosome number by half, producing four genetically diverse haploid cells.

What are the key features of meiosis?

Meiosis produces gametes with half the chromosome number of the parent cell and occurs only in germ cells.

What are the phases of meiosis?

Meiosis consists of two rounds of division: Meiosis I (Reduction Division) and Meiosis II (Equational Division).

What occurs during prophase I of meiosis?

In prophase I, chromosomes condense, homologous chromosomes pair up, and crossing over occurs.

What happens during metaphase I?

In metaphase I, homologous chromosome pairs align along the metaphase plate.

What occurs in anaphase I?

During anaphase I, homologous chromosomes are separated and pulled to opposite poles of the cell.

What happens during telophase I?

In telophase I, nuclear membranes may reform around the chromosomes, and the cell divides into two haploid cells.

What occurs in prophase II?

In prophase II, chromosomes condense again, and a new spindle apparatus forms.

What happens during metaphase II?

In metaphase II, chromosomes align along the metaphase plate in each haploid cell.

What occurs in anaphase II?

During anaphase II, sister chromatids are separated and pulled toward opposite poles.

What happens during telophase II?

In telophase II, nuclear membranes form around each set of chromosomes, resulting in four haploid cells.

How do mitosis and meiosis differ in purpose?

Mitosis is for growth, repair, and asexual reproduction, while meiosis is for sexual reproduction (formation of gametes).

What is the outcome of mitosis?

Mitosis produces two genetically identical diploid daughter cells.

What is the outcome of meiosis?

Meiosis produces four genetically diverse haploid cells.

What is the significance of genetic variation in meiosis?

Genetic variation arises from crossing over and independent assortment during meiosis, enhancing diversity in offspring.

What is the difference between diploid and haploid cells?

Diploid (2n) cells contain two full sets of chromosomes, while haploid (n) cells contain one set of chromosomes.

How do diploid cells produce haploid gametes through meiosis?

A diploid parent cell undergoes meiosis to produce haploid gametes, ensuring the correct diploid chromosome number upon fertilization.

What are the key features of mitosis?

Key features of mitosis include: Purpose - to produce two genetically identical daughter cells; Chromosome Number - remains the same as the parent cell (diploid); Types of Cells - occurs in somatic cells; Phases - includes Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.