Bio Chapter 1

• Viruses

  
  

  Can be living things in a proper host body, but has non living characteristics as they cannot respire, grow or move on their own.

  Nucleic acid and protein coat

  No cellular structure like cell membrane, organelles
• Light microscope

  magnify objects up to 1000x

  2D

  Coloured

  Shows the outline of organelles
• Electron microscope

  Magnify objects to more than 200 000x

  3D

  Black and white

  greater resolution

  Ultrastructure of cell
• 1mm = 1000um
• Magnification


  number of times the image of an object is larger than its actual size
• Calculate magnification - I/AM (must me same unit for image and actual)
• Red blood cells are eukaryotic cells
• Cell membrane

  Membranes are often found enclosing organelles, including nucleus, mitochondria, and golgi apparatus in eukaryotic cells
• Cell wall

  • made of cellulose
  • fully permeable
  • gives cell a fixed shape
• Bacteria

  Extra DNA in the form of plasmids

  
  

  Single celled organism with no membrane bound nucleus - singluar circular DNA.

  
  

  Some are pathogenic (disease causing) and some are non-pathogenic.

  
  

  All prokaryotic cells
• Prokaryotic cells

  - do not have a nucleus or other membrane-bound organelles

  - Simpler internal structure

  - DNA occurs as a sinlge loop

  - One or more plasmids

  - smaller in size

  - Cell wall

  - No mitochondria
• Eukaryotic cells

  - have a nucleus and other membrane-bound organelles

  - Compartmentalized internal structure

  - DNA is numerous linear strands

  - No plasmids

  - Larger in size

  - May or may not have cell wall

  - Mitochondria
• Similarities of Prokaryotes and eukaryotes

  DNA, cell membrane, ribosomes, cytoplasm
• Plasma membrane

  - forms physical boundary between cytoplasm and external environment

  - selectively permeable
• Double membrane bound organelles

  nucleus, mitochondria, chloroplast
• Cell wall

  - made of cellulose

  - fully permeable

  - gives cell a fixed shape
• Cytoplasm

  - Aqueous medium that contains dissolved substances and enzymes

  - contains all the organelles
• Nucleus

  - double membrane organelle

  - surrounded by nuclear membrane

  - contains genetic info in the form of chromosomes

  - essential for cell division

  - controls cell growth and the repair of worn out parts
• Organelle

  Any specialized structure within a cell that performs a specific function
• Chromatin

  Composed of mainly proteins and DNA

  - contains all genetic info that are essential for survival of the cell

  - when cell is dividing, chromatin threads condenses into tightly coiled structures called chromosomes
• Partially permeable

  Allows smaller molecules to pass though but exclude larger molecules e.g. visking tubing
• Selectively permeable

  Able to regulate the movement of substances according to the needs of the cell e.g. plasma membrane
• Rough ER

  - Network of flattened spaces

  - lined with a membrane

  - ribosomes attatched to the surface

  - synthesis of proteins for cell secretion
• Ribosomes

  - Small round structures attatched to RER or freely in the cytoplasm

  - synthesis of proteins in the cell

  - Ribosomes attatched to RER make proteins transported out the cell

  - Ribosomes lying freely make proteins used within cytoplasm
• Movement of proteins

  RER transports proteins made by ribosomes to the golgi body for secretion out of the cell.
• Smooth ER

  - more tubular than RER

  - connected to RER

  - synthesis of substances such as fats and steroids

  - detoxification: converts harmful substances like poison and drugs into harmless substances
• Golgi apparatus

  - stack of flattened spaces surrounded by membranes

  - vesicles fusing with one side of GA and pinching off from the opposite side

  - chemically modifies substances made by the ERs

  - stores and packages these substances in vesicles for secretion
• Mitochondria

  - aerobic respiration

  - energy produced in the form of ATP during respiration

  - bound by double membrane

  - numerous mitochondria in cells with high energy requirements
• Label microscope

  -

  A) ocular lens

  B) Head

  C) arm

  D) objective lens

  E) stage clip

  F) aperture

  G) diaphragm

  H) stage

  I) coarse adjustment

  J) fine adjustment

  K) stage controls

  L) condenser

  M) light source

  N) base

  O) light switch

  P) brightness adjustment

  Q) nose piece

  
• Movement of substance

  Vesicles containing substances made by the RER and SER are pinched off from the ER.

  • Vesicles fuse with the GA and release contents into GA for substance modification
  • Secretory vesicles containing modified substances are pinched off the GA, and move to the cell membrane
  • Secretory vesicles fuse with cell membrane and contents release out the cell
• Chloroplast

  • Contain chlorophyll and other photosynthetic pigments.
  • essential for photosynthesis
  • large double membrane bound organelle
• Vacuole

  • Fluid filled space, stores substances such as water and dissolved minerals within the cell
  • Surrounded by a single membrane known as tonoplast, which is a selectively permeable membrane
• Vacuole in plant cells

  Large central vacuole which contains cell sap, which contains dissolved substances such as sugars, mineral salts, and amino acids
• Vacuole in animal cells

  Many small vacuoles that contain water and food substances, and usually exist temporarily
• Excretory products that leave the cell

  Co2, Urea, amino acids
• Products that enter the cell

  water, oxygen, nutrients (amino acids)
• Cells develop structures of lose certain structures to enable them to carry out specific functions. e.g. root hair cell, red blood cell
• tissue - a group of cells that develop in the same way and have the same structure and function e.g. skeletal muscles
• organ - a group of tissues that work together to perform a specific function, e.g. the heart
• organ system - a group of organs that function collectively to perform a specific function e.g. digestive system