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The Central Dogma of Molecular Biology

Replication - General Characteristics:

• DNA replication is semiconservative: each strand in the DNA double helix acts as a template for the synthesis of a new, complementary strand. The new two daughter molecules of DNA have a new strand and an old one.
• DNA polymerase III: is the enzyme that adds nucleotides to the growing DNA chain, incorporating only those that are complementary to the template. DNA polymerase III has the following characteristics:
  • It can only read a template in 3’-----5’ direction so the new strand grows in 5’----3’ direction.
  • It needs a pre-existing strand of nucleotides called a primer which provides a 3’-OH end to bind new nucleotides.
  • It is able to repair the mistakes by removing

Properties of Metals

PROPERTIES OF METALS: good electrical, thermal and acoustic conductors; ductile and malleable; tough; they melt at high temperatures, expand when the temperature rises and contract when it cools; some are magnetic; rust when they come into contact with air and oxygen (not all); can be recycled and reused, some are toxic for the environment.

Ferrous Metals

FERROUS METALS: main component is iron.

PURE IRON: greyish white colour, good magnetic properties. Disadvantages: only melts at high temperature, difficult to machine, fragile and brittle. Uses: rarely used, used in electronics and electrical components. CAST IRON: very hard and resistant. Uses: machine parts, casing for engines, stands for machines, pistons, street lamps,... Continue reading "Properties of Metals and Ferrous vs. Non-Ferrous Metals" »

Just 2.5% of water on Earth is fresh water. About 69% of that fresh water is frozen. This means that less than 1% of water on Earth is drinkable.

1. The Atmosphere

1. The atmosphere

Earth's gaseous atmosphere is mostly nitrogen & oxygen. It also contains argon, carbon dioxide, ozone & water vapor.

Earth's atmosphere has an upper limit of 10,000 kilometers.

Most of the gases are found in the lowest 15 kilometers.

ATMOSPHERIC PRESSURE

The gases in the atmosphere push down on Earth's surface.

The weight of all these gases is called atmospheric pressure.

We measure atmospheric pressure in standard units called pascals. 1 standard atmosphere = 101.325 pascals.

There is more pressure at lower altitudes, near Earth's surface. There is less pressure at... Continue reading "Earth's Fluid Spheres: Atmosphere and Hydrosphere" »

Key Events of WW2

1939 September → Invasion of Poland (Trigger event)

1940 June → Germany invades France and defeats her in six weeks

1941 June - December → OPERATION BARBAROSSA

- Germany invades Russia. It is the largest military operation in history

1941 December → PEARL HARBOR

- Japan attacks on Pearl Harbor

1942 June → Battle of Midway

- The US Navy defeats the Japanese Navy.

1943 February → Stalingrad

- The German army surrenders at Stalingrad. One of the bloodiest battles, Hitler suffers a major defeat.

1944 June → Operation Overlord

- The Allies launch the largest assault in history on Normandy

1945 August → Hiroshima and Nagasaki

- The USA drops atomic bombs on Hiroshima and Nagasaki. 200.000 killing. Japan announces its surrenders.... Continue reading "Key Events, Causes, and Consequences of World War II" »

1. Bad-tempered (about): angry, annoyed

2. Cheerful (about): happy and positive

3. Content (with): pleased with your situation and not hoping for change or improvement

4. Down (about): unhappy and depressed

5. Fed up (with): annoyed or bored by something that you have experienced for too long

6. Irritated (by): annoyed

7. Optimistic (about: always believing that good things will happen

8. Anxious (about): worried and nervous

9. Concerned (about): worried

10. Depressed (about): unhappy and without hope for the future

11. Furious (with): Extremely angry

12. Over the moon (about): very pleased

13. Pessimistic (about): always believing that bad things are likely to happen

14. Petrified (of): extremely frightened

15. Relieved (about): happy that something unpleasant has not happened or has ended

16. Scared (of): frightened

DISTILATION PROCESS: ELEMENTS

• Thermometer: measure the temperature of the vapor
• The stopper: hold the thermometer
• The Bunsen Burner: heat the liquid
• The tube at the top of the condenser: conduct the cool water away
• The cool water: cool the vaporized alcohol
• The tube at the bottom of the condenser: conduct cool water in
• The receiving flask: collect the condensed alcohol
• The stand (soporte): maintain an upright or vertical position
• The clamps (pinzas): support the wire
• The wire gauze (rejilla de alambre): spread the flame out
• The ring clamps (pinzas de anilla): grip the flask and the condenser

ORDER

1. Distillation is used...
2. To separate a mixture of liquids...
3. Distillation is a widely used method...
4. The gas is then condensed...
5. Although the term is mostly common.

   anticyclone->air mass with high atmosph. Pressure

depression->air mass with LOW

S-H-depression->clockwise * N-H-anticyc->clock

isobar-lines of equal pressure/const.Pressure on weathe map

*heated air rises>air condenses,clouds form>descending air is dry>little rain falls here>sun heats ground>air rises cool>warm moist winds>rain falls

*Precipitation zones>humid warm,dry warm,humid tempe,dry cold

*clouds>cirrus,stratus,cumulus,nimbus,altocumulus,numbostratus

*precipitation factors>air pressure,humidity,ocean currents,atmospheric circulation,

*air mass>arctic and antarctic->cold and dry, polar air mass, tropical, equatorial

*fronts->warm,cold,stationary,occluded

*cyclone>N.H.-anti,  S.H.-clock

*... Continue reading "Given dry operating mass 5210 zero fuel mass" »

Receptors

Internal receptors perceive changes inside the body, such as a rise in blood pressure. External receptors perceive stimuli in the external environment.

Types of Receptors

• Mechanoreceptors: Perceive mechanical stimuli (pressure).
• Thermoreceptors: Perceive changes in temperature.
• Chemoreceptors: Detect chemical substances in the air, water, etc.
• Nociceptors: Perceive pain stimuli.
• Photoreceptors: Light sensitive.

Nervous System

The nervous system analyzes internal and external stimuli perceived by receptors, generating responses. It carries out this function through nerve impulses transmitted by cells called neurons. This system coordinates fast, short-lived responses (e.g., muscle contraction).

Endocrine System

The endocrine system is made up... Continue reading "Sensory Systems and Nervous Coordination" »

Sternocleidomastoid

Origin:

• Sternal head: Manubrium of sternum
• Clavicular head: Medial 1/3 of clavicle

Insertion: Outer surface of mastoid process, lateral 1/3 of superior nuchal line
Nerve Supply:

• Motor: Accessory nerve
• Sensory: C2, C3

Action:

• Both muscles contract: Flexes neck forward
• One muscle contracts: Bends neck to the opposite side and rotates to the same side

Relations:

• Superficial: Skin
• Deep: Carotid sheath

Digastric Muscle

Origin:

• Anterior belly: Lower border of mandible
• Posterior belly: Digastric notch of mastoid process

Intermediate tendon: Connected to hyoid bone
Nerve Supply:

• Anterior belly: Mylohyoid nerve
• Posterior belly: Facial nerve

Function:

• Anterior belly: Depresses mandible, elevates hyoid bone
• Posterior belly: Elevates hyoid bone, retracts mandible

Relations: