Notes, abstracts, papers, exams and problems of Biology

• Many carbon-based molecules are made of many small subunits bonded together.
• Monomers are the individual subunits.
• Polymers are made of many monomers.
• Four main types of carbon-based molecules are found in living things.
• Carbohydrates are made of carbon, hydrogen, and oxygen. Include sugars and starches. Carbohydrates can be broken down to provide energy for cells. Some carbohydrates are part of cell structure.
• Monosaccharides are simple sugars.
• Polysaccharides include starches, cellulose, and glycogen.
• Polymer (starch)
• Starch is a polymer of glucose monomers that often has a branched structure.
• Polymer (cellulose)
• Cellulose is a polymer of glucose monomers that has a straight, rigid structure
• Many contain carbon chains called fatty acids.
• Fats and oils

Gene and Alleles

• A gene is a unit of heredity that occupies a specific locus on a chromosome.
• A locus is a specific location on a chromosome where a gene is located.
• Alleles are different forms of a gene that occupy the same locus on homologous chromosomes.

Hardy-Weinberg Equilibrium

• The Hardy-Weinberg equilibrium is a population genetics model that describes the frequencies of alleles and genotypes in a population that is not evolving.
• The five conditions for Hardy-Weinberg equilibrium are:
  1. No mutation
  2. No gene flow
  3. No genetic drift
  4. Random mating
  5. No natural selection

Population Genetics

• Population genetics is the study of the genetic variation within populations.
• Genetic variation is the presence of different alleles in a population.
• The gene pool is the

Photosynthesis produces glucose using

Photosynthesis produces food in plants, called glucose. It happens in chloroplasts. Chloroplasts contain chlorophyll, that absorbs sunlight and uses its energy to convert carbon dioxide and water into glucose. Oxygen is also produced. EQUATION: CARBON DIOXIODE + WATER= GLUCOSE + OKYGEN. Photosynthesis converts light energy into chemical energy.

Adaptation for efficient photosynthesis

Leaves are broad so there is a large surface area exposed to light. Most of chloroplasts are found in the palaside layer. This is so that they are near the top of the leaf where they can get the most light. The upper epidermis is transparent so that light can pass through it to the palisade layer. Leaves have a network of vascular... Continue reading "Photosynthesis and Efficient Adaptations for Multicellular Organisms" »

Darwin and the Theory of Natural Selection

The principal merit of Darwin's theory, in addition to the many evidence that he provided to it, is the discovery of the mechanism that governs the entire evolutionary process of species: the natural selection.

1. Firstly, when environmental resources become scarce, an inevitable competition occurs and, consequently, the struggle for survival begins in which most individuals die.
2. Secondly, it is also obvious that individuals of the same species have different features or characteristics that appear randomly and make individuals different from each other.
3. Third, these characteristics make some individuals more advantaged than others. Those whose characteristics are favorable to the demands of the environment

All Cells Form from Existing Cells

• Centipedes: 1 pair of legs per each section
• Millipedes: 2 pairs per each section

• All organisms are composed of one or more cells
• The cell is the basic unit of life in all living things
• Cells are produced by the division of pre-existing

Excretion

Elimination of waste substances from blood is performed by the urinary system and other organs.

Urinary System

• Kidneys: bean-shaped organs behind the abdomen, filtering blood to form urine.
• Ureter: thin tubes transporting urine to the bladder.
• Urinary bladder: elastic bag storing urine.
• Urethra: duct transporting urine outside.

Other organs involved in excretion are lungs, liver, and sweat glands.

The Circulatory System

Function: Transporting O2, nutrients, and collecting CO2 and waste substances.

Blood

• Blood Plasma: 55% of blood, transporting nutrients, waste substances, and CO2.
• Blood Cells: red blood cells, white blood cells, and platelets.

Blood Vessels

Arteries, veins, and blood capillaries carry blood around the body.

Heart

Hollow muscular... Continue reading "Excretion and Circulatory System Overview" »

Protein Structure:

It is a three-dimensional structure. Polypeptides are folded to produce a globular shape. The structure is stabilized by intermolecular bonds between amino acids.

Primary Structure:

Is the sequence of amino acids in the polypeptide chain. It is codified by a gene. The sequence of nucleotides in a gene codify the sequence of amino acids in a polypeptide chain.

Secondary Structure:

3-dimensional conformation. It's the formation of beta-pleated and alpha helices, established by hydrogen bonds. It's the bond formed between the carboxyl group and the amino group.

Tertiary Structure:

The polypeptide chain is folded and established by interactions between R groups. The conformation is established by intramolecular bonds and interactions... Continue reading "Protein Structure and Functions" »

Polymerization –plus and minus ends of actin, Kd, critical concentration, phases of growth of polymers (lag, growth, and steady-state), nucleating factors, why growth occurs preferentially at plus end.

a.High Kd and Cc= ADP + Factin lower affinity actin so dissociate

b.Lower kd and Cc= Gactin/Factin + ATP higher affinity actin so dissociate

c.Profilin and thymosin: Profilin binds to (-) end = plus end grow fast

d.Thymosin buffer + actin monomer = prevent polymerization or ATP hydrolysis.

e.Actin monomer (is above Kd) & regulates actin filament assembly.

Arp2/3 comples to make a seed (nucleate) acting growth. Can create tree-like web

Myosin II structure: motor protein makes force in skeletal contraction muscles.

a.Heavy chain with NT head (ATPase... Continue reading "Cell Biology: Actin, Myosin, and Microtubules" »

A Minimal pair is a pair of words that vary by only A single sound, usually meaning sounds that may confuse English learners, like The /f/ and /v/ infanandvan, Or the /e/ and /ɪ/ indeskanddisk

Minimal Pairs /ɪ/ and /i:/sit Seat

Minimal Pairs /e/ and /ɪ/desk disk

Minimal Pairs /e/ and /eɪ/wet wait

Minimal Pairs /æ/ and /ʌ/bat but

Minimal Pairs /əʊ/ and /ɔ:/sosaw

Minimal Pairs /ɒ/ and /əʊ/not note

Minimal Pairs /æ/ and /e/bad bed

Minimal Pairs /ɑ:/ and /ɜ:/fast first

Consonant Sounds

Minimal Pairs /b/ and /v/berryvery

Minimal Pairs /b/ and /p/buypie

Minimal Pairs /n/ and /ŋ/thinthing

Minimal Pairs /l/ and /r/alive arrive

Minimal Pairs /ʧ/ and /t/catchcat

Minimal Pairs /s/ and /ʃ/seashe

Minimal Pairs /f/ and /v/fanvan

Minimal Pairs /f/ and /h/