Cellular biology

• Organelles in a cell include:

  • Golgi Apparatus (Gogli bodies): collects and processes materials to be removed from the cell
  • Lysosomes: membrane-bound organelles that digest biological material
  • Cell Membrane: flexible membrane surrounding the cell, semi-permeable
  • Cytoskeleton: network of proteins forming the internal framework of the cell, providing support and the ability to change the cell's shape
• Ribosomes: the protein that makes proteins
• Mitochondria: where cellular respiration takes place, producing the energy cells use; active cells have more mitochondria
• Nucleus: central center of the cell, containing the genetic information (DNA) of the cell
• Nucleolus: produces and assembles ribosomes for the cell
• Rough Endoplasmic Reticulum (Rough ER): transports material such as proteins through the cell; ribosomes cover its surface
• Smooth Endoplasmic Reticulum (Smooth ER): makes lipids and detoxifies poisons; transports these through the cell
• Chromosomes: the structure of DNA in the nucleus of the cell, containing all the genetic information
• Centrioles: barrel-shaped organelles responsible for producing spindle fibers during cell division (mitosis)
• Vesicles: help transport materials that an organism needs to survive and recycle waste material
• Vacuoles: store and release water
• Discovery of the cell:

  • Robert Hoole in 1665 observed cork cells, named them "cells because they reminded him of the cells of a monastery
  • Anton Van Leeuwenhoek in 1674 was one of the first to observe living cells, calling them "animalcules" in Latin for "little animals"
  • Mattias Schleiden in 1838 proposed the idea that plants are made of cells.
  • Theodor Schwann concluded that all animals are made of cells.
• Cell Theory:

  • Theodor Schwann concluded that all animals are made of cells.
  • Rudolf Virchow in 1855 concluded that cells can only come from pre-existing cells, rejecting spontaneous generation
• Cell divisions happen for reproduction, growth, and repair
• DNA stands for Deoxyribonucleic acid
• The four building blocks of DNA nucleotides are:

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
• Chromosomes are tightly packed DNA and histone protein structures
• Histone is a protein molecule that DNA wraps itself around
• Chromatin is the thin thread of DNA that condenses before mitosis
• Chromatid is one strand of DNA before replication
• Sister chromatids are two identical DNA strands connected by the centromere, forming a copy after DNA replication
• Homologous chromosomes are a pair of chromosomes with identical features, one paternal and one maternal
• Humans have 46 chromosomes (2n), the diploid number of chromosomes in a normal cell
• Haploid (n) cells contain only one of each chromosome, with n=23 found in sperm and egg cells
• Cell Cycle:

  • Interphase: majority of a cell's life, performing normal functions

  1. G1 (Growth or GAP phase): cell recovers from previous division
  2. S phase (Synthesis): cell grows in size, increases in organelles
  3. G2 Phase: Replication (now cell has 2 chromatids)

  • G0 Phase: cell is in a resting phase, performing normal functions but not dividing
• Mitosis is nuclear division
• Telophase.

  Spindle fibers break down .Nuclei begin to form around chromosomes. Chromosomes begin to unwind

  • Cytokinesis:
  • Division of cytoplasm
  • When cytokinesis does not occur, there is a multinucleate cell
• Structures of Mitosis:

  • Centrosomes:
  • Composed of centrioles and proteins
  • Located beside the nucleus, assisting in cell division
  • There are 2 centrosomes per cell during cell division
  • Centrioles:
  • Barrel-shaped organelles located in centrosomes' protein structure
  • Organize the mitotic spindle, which consists of fibers of microtubules
  • Spindle fibers (Microtubules) in Mitosis:
  • Prophase:
  • Chromatin condenses
  • Nucleolus breaks down and disappears
  • Mitotic spindle starts to form
  • Metaphase:
  • Responsible for moving chromosomes around the cell during mitosis
  • Anaphase:
  • Sister chromatids separate
  • Spindle fibers shorten, pulling chromatids to opposite ends of the cell
  • Telophase:
  • Spindle fibers attach to chromosome centromeres
  • Chromosomes are aligned in the middle of the cell (metaphase)
• Centrosomes:

  • Composed of centrioles and proteins
  • Located beside the nucleus, assisting in cell division
  • There are 2 centrosomes per cell during cell division. Centrioles:
  • Barrel-shaped organelles located in centrosomes' protein structure
  • Organize the mitotic spindle, which consists of fibers of microtubules