Cell Structure

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Cell Structure

• Analysis of the functional inter-relationships of
  cell structures

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Cell Biology the study of cells the structural
and function units of all living organisms
morphologically cells vary in shape and size
red blood cells
human sperm cells
bacteria
white blood cells
nerve cell
platelets
cancer cells (myeloma)
cells also vary physiologically
portion of skeletal muscle cells
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Cell Theory

• Cells
• Cells come from cells

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Nucleus and Nucleoid
a nucleoid (which consists of the organisms DNA)
is NOT enclosed in a membrane prokaryotic cell
eukaryotic cell DNA contained within a membrane
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Eukaryotic Cells

• Bounded by cell
• Cytoplasm inside cells composed of aqueous
  solution, organelles and molecules
• Various fibres compose a to give shape and
  structure

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Nucleus

• Contains genetic material which controls/directs
  the activities of the cell
• function brain of cell, i.e. determines
  metabolism, growth, differentiation,
  reproduction of cell
• Nucleus enclosed in a nuclear envelope
• Within is chromosome/chromatin, nucleoplasm
  and nucleoli
• are long strands of DNA wrapped around
  protein molecules which make up genes (units of
  heredity)
• nucleoplasm is a highly viscous liquid
• is the site where rRNA is assembled (rRNA then
  travels to the cytoplasm for protein syntheis)

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DNA packed in Chromosomes
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Chromatin vs. Chromosome
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Ribosome

• consist of 2 nonidentical subunits formed from
  rRNA proteins
• function protein synthesis
• found attached to endoplasmic reticulum or free
  in cytoplasm
• group of ribosomes simultaneously
  synthesizing same protein

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Membranous Canals

• Includes endoplasmic reticulum, golgi apparatus,
  vacuoles and lysosomes

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Endoplasmic Reticulum

• Series of canals exist in cytoplasm
• Can extend from envelope to cell membrane
• rough endoplasmic reticulum
• ribosomes attached to surface
• function synthesize proteins for secretion
• NOTE unlike free ribosomes that synthesize
  proteins for use within cell
• smooth endoplasmic reticulum
• no ribosomes attached to surface
• functions
• synthesis of lipids, e.g. cell membrane
  hormones
• metabolism of carbohydrates, e.g. synthesis of
  glycogen
• detoxify drugs wastes in cell, e.g. alcohol

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Golgi Apparatus

• resembles stack of hollow tubes,
• i.e. similar to smooth endoplasmic reticulum,
  but closer to cell membrane
• function sorting, modification (assembly),
  packaging of substances for storage or
• e.g. produces glycolipids by joining
  carbohydrates to lipids
• receives vesicles from endoplasmic reticulum that
  contain newly synthesized proteins/lipids
• proteins/lipids sorted, modified, packaged
  into new vesicles that bud off
• transported within cell or moved to cell
  membrane for export by exocytosis

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Vacuoles

• large, membrane enclosed sac
• vesicle small
• storage or transport
• formed by
• 1. budding (pinching off) from Golgi apparatus
• 2. endocytosis of
• 3. extension of endoplasmic reticulum membrane

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Lysosomes

• vesicle formed by Golgi apparatus, which contains
  hydrolytic enzymes
• functions
• 1. cellular digestion of food particles, i.e.
  fuses with food vacuoles enzymatically digests
  proteins, carbohydrates, lipids
• 2. disposal of damaged cell organelles, e.g.
  mitochondria
• 3. breakdown of whole cell, i.e. releases
  contents into cell cytoplasm

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Energy related organelles
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Mitochondria

• function cellular respiration (aerobic
  metabolism), i.e. converts glucose
  (carbohydrates) to energy (ATP)
• chemical reaction
• cristae (singular crista) shelflike structures
  formed from folded inner membrane with enzymes on
  surface for cellular respiration
• Provides lots of surface area for cell. resp.
  reaction.
• matrix solution surrounded by
• cristae contains DNA

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Choloroplast

• function in plant cells, i.e. converts
  sunlight energy to carbohydrates
• Made up of membranous stacks called grana, which
  contain chlorophyll pigments
• chlorophyll chemical that absorbs sunlight
  energy allows photosynthesis to occur

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Basic Photosynthesis

• Works hand in hand with cellular respiration

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Organelles made up of Membranes

• Nuclear envelope
• Endoplasmic reticulum
• Golgi apparatus
• Lysosomes
• Vacuoles
• Vesicles
• Cell membrane
• Mitochondria
• Chloroplast
• Note Membranes are composed of phospholipids

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Cell Shape
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Other Organelles

• Cell wall
• rigid cellular layer that the cell membrane in
  plant cells
• Provides , shape, and for the cell
• Composed of cellulose
• Cytoskeleton
• network of protein fibres
• functions cell shape, anchor organelles,
  involved in

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Characteristics of Living Things

• Living are made of cells.
• Living things obtain and use energy.
• Living things grow, reproduce and repair.
• Living things produce .
• Living things to their environment.
• Living things a life span.

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By the end of this section you should be able to

• Prokaryotic cell verses a eukaryotic cell
• Describe the following cell structures and their
  functions
• Cell membrane
• Cell wall
• Chloroplast
• Cytoskeleton
• Cytoplasm
• Golgi bodies
• Lysosomes
• Mitochondria including cristae and matrix
• Nucleus - including nuclear pore, nucleolus,
  chromatin, nuclear envelope, and chromosomes
• Ribosomes (and polysomes)
• Smooth and rough endoplasmic reticulum
• Vacuoles
• Vesicles
• State the balanced chemical equation for cellular
  respiration and photosynthesis
• Describe how the following organelles function to
  compartmentalize the cell and more materials
  through it
• Rough ER and smooth ER
• Vesicles

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