Eight Major Organelles - Nucleus Overview

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Questions and Answers

What is the control center of the cell?

nucleus

What surrounds the nucleus?

  • Endoplasmic reticulum
  • Cell membrane
  • Ribosomes
  • Nuclear envelope (correct)

Humans have 46 chromosomes in every cell.

False (B)

What are ribosomes made out of?

<p>proteins and rRNA</p> Signup and view all the answers

What type of ribosomes are found in the cytoplasm?

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

What is the function of the rough endoplasmic reticulum (RER)?

<p>Protein folding and processing</p> Signup and view all the answers

What is produced in the smooth endoplasmic reticulum (SER)?

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

What is the control center of the cell?

<p>Nucleus</p> Signup and view all the answers

The nuclear envelope is a single membrane structure.

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

What type of RNA do ribosomes use to translate information?

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

Humans have __ chromosomes in every cell.

<p>23</p> Signup and view all the answers

What are the two types of Endoplasmic Reticulum?

<p>RER and SER</p> Signup and view all the answers

What is the function of the Rough Endoplasmic Reticulum (RER)?

<p>Protein folding and transport (A)</p> Signup and view all the answers

Match the following ribosome types with their functions:

<p>Free ribosomes = Make proteins used within the cytoplasm Bound ribosomes = Make proteins for cell membrane or export</p> Signup and view all the answers

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Study Notes

Nucleus

  • Serves as the cell's control center, housing genetic material.
  • Contains DNA organized into structures called chromosomes; humans have 23 chromosomes per cell.
  • Enclosed by a double membrane known as the nuclear envelope, which separates nuclear contents from cytoplasm.
  • Features nuclear pores that allow selective transport of substances in and out of the nucleus.
  • Pore complexes consist of proteins that regulate the passage of molecules through the nuclear pores.

Ribosomes

  • Composed of ribosomal RNA (rRNA) and proteins, they are essential for protein synthesis.
  • Translate messenger RNA (mRNA) sequences to assemble amino acids into proteins.
  • Free ribosomes float in the cytoplasm, synthesizing proteins for internal cellular use.
  • Bound ribosomes are attached to the endoplasmic reticulum (ER), producing proteins for membrane incorporation or export outside the cell.

Endoplasmic Reticulum (ER)

  • Divided into two types: Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).

Rough Endoplasmic Reticulum (RER)

  • Characterized by ribosomes bound to its surface, giving it a "rough" appearance.
  • Continuous with the nuclear membrane, facilitating direct communication.
  • Ribosomes synthesize proteins that are threaded into the RER, where they fold into functional shapes and are packaged into vesicles for transport.

Smooth Endoplasmic Reticulum (SER)

  • Lacks ribosomes; involved primarily in lipid synthesis.
  • Responsible for the production of steroids, phospholipids, and oils, contributing to the formation of cellular membranes.

Nucleus

  • Acts as the cell’s control center, housing DNA.
  • Encased in a double membrane known as the nuclear envelope.
  • The envelope features tiny pores for selective substance exchange between the nucleus and cytoplasm.
  • Nuclear pore complexes regulate the movement of materials, ensuring proper communication and control.
  • Chromatin organizes into chromosomes, with humans possessing 23 pairs in each cell.
  • Chromosomes remain loosely coiled for access to genetic information.

Ribosomes

  • Composed of proteins and rRNA (ribosomal RNA).
  • Responsible for translating messenger RNA (mRNA) instructions to synthesize proteins.
  • Free ribosomes operate in the cytoplasm, producing proteins for internal cellular use.
  • Bound ribosomes, attached to the endoplasmic reticulum (ER), synthesize proteins for incorporation into membranes or export outside the cell.

Endoplasmic Reticulum

  • Divided into two types: Rough Endoplasmic Reticulum (RER) and Smooth Endoplasmic Reticulum (SER).

RER

  • Characterized by attached ribosomes, appearing “rough” under a microscope.
  • Continuous with the nuclear membrane, facilitating protein production and processing.
  • Newly synthesized proteins enter the RER through pores, where they fold into functional shapes.
  • Proteins exit the RER encased in vesicles for further transportation.

SER

  • Lacks ribosomes, giving it a smooth appearance.
  • Primarily involved in lipid synthesis, producing steroids, phospholipids, and oils essential for various cellular functions.

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