Biologie - Replicarea ADN-ului și Enzimele
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Care dintre următoarele afirmații descrie cel mai bine procesul de replicare a ADN-ului?

  • Replicarea ADN-ului se produce fără intermediari.
  • Toate moleculele de ADN nou create sunt complet identice cu originalul.
  • ADN-ul se replică printr-un mecanism semi-conservativ, păstrând o strandă originală. (correct)
  • Se formează două molecule de ADN identice, fiecare dintr-o rețea complet nouă.

Care dintre următoarele opțiuni reprezintă un factor care influențează activitatea enzimelor?

  • Temperatura și pH-ul mediului. (correct)
  • Numărul de molecule de apă din celulă.
  • Tipul de substrat utilizat în reacție.
  • Dimensiunea ADN-ului din celulă.

Ce se întâmplă în stadiul de metafază al mitozei?

  • Strândele de cromozomi se decondensează.
  • Fibrele de fus se destramă.
  • Cromozomii sunt separați în două celule fiice.
  • Cromozomii se aliniază la placa metafazică. (correct)

Care dintre afirmațiile următoare referitoare la meioză este corectă?

<p>Meioza duce la formarea a patru celule haploide unique. (D)</p> Signup and view all the answers

Ce rol are ADN-polimeraza în replicarea ADN-ului?

<p>Sintezează noi stranduri complementare la strandurile originale. (D)</p> Signup and view all the answers

În ce stadiu din mitoză are loc separarea cromatidelor surori?

<p>Anafaz (D)</p> Signup and view all the answers

Ce tip de celule sunt rezultatul mitozei?

<p>Celule identice din punct de vedere genetic. (C)</p> Signup and view all the answers

Care este importanța enzimelor în reacțiile biochimice?

<p>Ele accelerează reacțiile prin scăderea energiei de activare. (D)</p> Signup and view all the answers

What is the primary outcome of meiosis?

<p>Four genetically unique haploid cells (A)</p> Signup and view all the answers

During which phase of meiosis do homologous chromosomes separate?

<p>Anaphase I (D)</p> Signup and view all the answers

Which process introduces genetic variation during meiosis?

<p>Crossing over (C)</p> Signup and view all the answers

What occurs during Telophase I and Cytokinesis in meiosis?

<p>Two haploid daughter cells are formed (A)</p> Signup and view all the answers

How does Meiosis II primarily differ from Mitosis?

<p>Meiosis II occurs after a single round of DNA replication (A)</p> Signup and view all the answers

What characterizes the semiconservative nature of DNA replication?

<p>One new strand is paired with one original strand. (A)</p> Signup and view all the answers

Which enzyme is responsible for unwinding the DNA double helix during replication?

<p>Helicase (A)</p> Signup and view all the answers

Which of the following factors does NOT influence enzyme activity?

<p>Cell size (C)</p> Signup and view all the answers

What happens during anaphase of mitosis?

<p>Sister chromatids separate and move to opposite poles. (A)</p> Signup and view all the answers

How does the competitive inhibitor affect enzyme activity?

<p>It competes with the substrate for the active site. (D)</p> Signup and view all the answers

In which phase of mitosis do spindle fibers begin to disappear?

<p>Telophase (B)</p> Signup and view all the answers

What is the main function of DNA polymerase III in DNA replication?

<p>Adds nucleotides to the DNA strand. (B)</p> Signup and view all the answers

What must happen for an enzyme to reach its maximum activity due to substrate concentration?

<p>Substrate concentration must reach saturation. (A)</p> Signup and view all the answers

Flashcards

Replicări ADN

Procesul prin care o celulă își dublează ADN-ul.

Enzime

Catalizatori biologici care accelerează reacțiile biochimice.

Mitosă

Tip de diviziune celulară care produce două celule fiice identice.

Meioză

Tip specializat de diviziune celulară care produce patru celule fiice unice genetic.

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Profază (Mitosă)

Etapa mitoză în care cromozomii se condensează, membrana nucleară se dezintegrează, iar fibrele fusului se formează.

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Metafază

Etapa în care cromozomii se aliniază la placa metafazică (centrul celulei).

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Anafază

Etapa în care cromatidele surori se separă și se deplasează către poli opuși.

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Telofază

Etapa finală a mitoză unde cromozomii se decondensază, se formează membrane nucleare, și începe diviziunea celulei.

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What happens during cytokinesis?

The cytoplasm divides, forming two separate daughter cells.

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Meiosis I: What happens in Prophase I?

Homologous chromosomes pair up (synapsis) and exchange genetic material (crossing over).

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Meiosis I: Metaphase I

Homologous chromosome pairs align at the metaphase plate.

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Meiosis II: What's the difference from Mitosis?

Meiosis II is similar to mitosis, but with haploid cells. So sister chromatids separate, instead of homologous pairs.

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What is the outcome of Meiosis?

Four haploid daughter cells are formed, each genetically unique due to crossing over.

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DNA Replication

The process of copying a DNA molecule to produce two identical DNA molecules. It is crucial for cell division and the transmission of genetic information. It is a semiconservative process, meaning that each new DNA molecule consists of one original strand and one new strand.

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Origins of Replication

Specific sites on a DNA molecule where DNA replication begins.

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Helicase

An enzyme that unwinds the DNA double helix during DNA replication.

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DNA Polymerase III

An enzyme that adds nucleotides to the primers to form the new DNA strands, in a 5' to 3' direction during DNA replication.

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Enzyme Activity

The rate at which an enzyme catalyzes a biochemical reaction.

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Optimal Temperature

The temperature at which an enzyme exhibits maximum activity.

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Competitive Inhibitor

A substance that binds to the active site of an enzyme, competing with the substrate for the active site.

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Study Notes

Biology, Genetics, Cell Biology

  • Biology is the scientific study of life, encompassing various levels from molecules to ecosystems.
  • Genetics is the field of biology focusing on heredity and variation in living organisms.
  • Cell biology examines the structure, function, and behavior of cells.

DNA Replication

  • DNA replication is the process by which a cell duplicates its DNA.
  • This process is essential for cell division and the transmission of genetic information.
  • The process involves unwinding the DNA double helix, separating the two strands.
  • DNA polymerase synthesizes new strands complementary to the original strands.
  • Errors during replication can lead to mutations.
  • Replication occurs in a semi-conservative manner. Each new DNA molecule consists of one original strand and one newly synthesized strand.

Enzyme Activity

  • Enzymes are biological catalysts that accelerate biochemical reactions.
  • They typically work by lowering the activation energy required for a reaction to occur.
  • Enzyme activity is influenced by factors like temperature and pH.
  • Each enzyme has a specific active site that binds to a specific substrate.
  • Enzyme-substrate complexes form, where the reaction occurs.
  • Products are released from the complex, leaving the enzyme unchanged.

Stages of Mitosis

  • Mitosis is a type of cell division resulting in two identical daughter cells.
  • It's a crucial process for growth, repair, and asexual reproduction.
  • Stages involved:
    • Prophase: Chromosomes condense, nuclear envelope breaks down, spindle fibers form.
    • Metaphase: Chromosomes align at the metaphase plate (center of the cell).
    • Anaphase: Sister chromatids separate and move to opposite poles.
    • Telophase: Chromosomes decondense, nuclear envelopes reform, and the cell begins to divide.

Stages of Meiosis

  • Meiosis is a specialized type of cell division that produces four genetically unique daughter cells.
  • Crucial for sexual reproduction.
  • It involves two rounds of division (Meiosis I and Meiosis II).
  • Key differences from mitosis include:
    • Homologous chromosome pairing and crossing over in Meiosis I
    • Separation of sister chromatids in Meiosis II
  • The result is four haploid cells, each with half the number of chromosomes as the parent cell.

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Description

Acest quiz explorează conceptele fundamentale ale biologiei, concentrându-se pe replicarea ADN-ului și activitatea enzimelor. Vom discuta despre importanța replicării ADN-ului pentru diviziunea celulară și rolul enzimelor ca catalizatori biologici. Testați-vă cunoștințele în aceste domenii esențiale ale biologiei.

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