Parts of the cell

BIOCHEMISTRY 3(2+1)
Lesson 4 : Cell Structure and Functions

Parts of the cell

The parts of the cell can be divided as
  1. Nucleus
  2. Cytoplasm
  3. Surface or cell wall

Nucleus

  • One or more per cell
  • Spherical shape
  • Denser than surrounding cytoplasm
  • The nucleus consists of the nuclear envelope, nucleolus, chromatin, and nucleoplasm.

Nuclear Envelope

  1. Structure
      • two unit membranes with a fluid-filled space
      • nuclear pores present
      • outer membrane may be continuous with endoplasmic reticulum
  2. Function selectively permeable to control movement in or out contains nuclear contents

Chromatin

  1. Structure -composed of long thin strands of DNA
  2. Function -contains instructions that control cell metabolism and heredity

Nucleolus

  1. Structure non-membraneous matrix of RNA (ribonucleic acid) and protein
  2. Function
      • instructions in DNA are copied here
      • works with ribosomes in the synthesis of protein

Chromosomes

  • Usually in the form of chromatin
  • Contains genetic information
  • Composed of DNA
  • Thicken for cellular division
  • Set number per species (i.e. 23 pairs for human)
df

Nuclear membrane

  • Surrounds nucleus
  • Composed of two layers
  • Numerous openings for nuclear traffic
g

Nucleolus

  • Spherical shape
  • Visible when cell is not dividing
  • Contains RNA for protein manufacture
f
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Last modified: Tuesday, 17 January 2012, 9:08 AM