Bio on DNA stuff

Senses

• Sense organs are made up of sensory receptor cells that detect stimuli\

• Sensation- raw input from the receptor in the PNS arriving at CNS

• Transduction- translation of stimulus into electrical signals.

• Perception- interpretation of the sensations in the CNS

General Senses

• Touch

• Temperature 

• Pain

Special Senses

• Smell and taste

  • Airborne detected by those in the nose (olfaction)

  • Close range detected by those in the tongue (taste buds)

  • Both are chemoreceptors.

• Vision

• Hearing 

Senses of the Skin

• Touch/pressure- mechanoreceptors

• Temperature- thermoreceptors

• Injury/Extreme heat or cold- pain receptors.

Sensory Neurons

• Touch Discrimination- ability to identify type and source of touch stimulus.

• Constant stimulation leads to fewer action potentials: sensory adaptation.

Sensory Adaptation

• Type of sense

  • Quick adapters: smell and touch – familiar non-essential stimuli

  • Slow adapters: pain and extreme temps – protective, prevents harm

• Nature of Stimuli

  • Constant stimulation- Easily adapted to → shifts focus to new information.

  • Changing or intense stimuli→ need to notice

  • Anticipated or familiar stimuli adapt quicker.

Vision

• Photoreceptors detect light

  • Rod and cone cells at the back of the eye.

• Light passes through the cornea and through the pupil, allowing light to pass through and go into the eye.

• The lens bends the light, which converges at the retina.

• Order

  • Cornea, pupil, lens, retina

• Nearsightedness or Farsightedness

  • It occurs when lights rays focus at a point other than directly on the retina

Hearing

• The cochlea, cilia on the hair cells move and transmit the signal to the auditory nerve.

• Mechanoreceptors of the inner ear detect vibrations

Together the senses send information to the brain about the environment – both internal and external, which ultimately helps the body maintain homeostasis.

10/22/2024

What is DNA?

• DNA Stores information that the cell needs to produce proteins

• DNA is a double helix

• Scientists that discovered this: Franklin, Watson and Crick

• DNA is a nucleic acid, monomers=nucleotides

  • Phosphate 

  • Sugar

  • Nitrogen

  • Containing base

    • Adenine (A)

    • Guanine (G)

    • Thymine (T)

    • Cytosine ©

  • Adenine (A) Binds to Thymine (T)

  • Guanine (G) Binds to Cytosine © 

• Ladder Analogy

  • S - Base pair - S

  • P                      P

    • Sugar - phosphate “Sides”

    • Base pairs form the “rings”

• H bonds connect complementary DNA strands

• Covalent bonds join the sugar phosphate sides.

  • Hydrogen bonds are in the middle and covalent bonds are on the sides.

• Main function of DNA- encode proteins. 

• A gene is a sequence of DNA that encodes a specific protein.

• Protein production occurs in 2 stages:

  • Transcription

    • Produces an RNA molecule that is complementary to DNA

  • Translation 

    • The information in RNA is used to make a protein.

DNA v. RNA

• DNA

  • Sugar = deoxyribose

  • Bases include A,T,C and G

  • Double stranded

• RNA

  • Sugar = ribose

  • Bases include A, U, C, and G

  • Single stranded

  • Not proteins

• Transcription occurs in the nucleus.

  • DNA pairs with RNA

  • A-U

  • C-G

  • And vise versa

• Translation

  • RNA → Protein

  • Happens at the ribosome

  • The genetic code shows which mRNA codons correspond to which amino acid.

• A codon is a 3 nucleotide sequence (on the mRNA) that encodes 1 amino acid.

• Transfer RNA (tRNA) molecules “translate” the genetic code. One end contains the anticodon, while the other end is linked to an amino acid.

• Transcription - Nucleotides to nucleotides

• Translation- nucleotides to amino acids

• Translation is efficient when multiple ribosomes attach to an mRNA molecule simultaneously.