Biomolecules:

Part 1 – Carbohydrates

 Monosaccharides: starch, cellulose, chitin…etc.

o Structural support
o Intercellular communication
o Source of and storage of cellular energy
o Covalently linked (polymerized)
 Polysaccharides: chain of sugars
o Linked by glycosidic bonds
 Glucose: monosaccharide
o Aldehyde group
 Fructose: monosaccharide
o Ketone group

Benedict’s Test

 Tests reducing sugars

o Containing aldehyde of ketone functional groups
o Monosaccharides and disaccharides have
o Polysaccharides don’t
 Reagent contains Cu2+ in alkaline solution
o Linearizes monosaccharides
o Shows carbonyl groups
 Carbonyl groups reduces Cu2+ to Cu+
o Forms red precipitate
 Red precipitate = reducing sugar
 Aldehyde group is hidden in polysaccharides
o Won’t expose the group
o Test will be negative (solution stays blue)
 Testing water = control group

Lugol’s Test

 Tests starch
o Polysaccharide formed of glucose
 Reagent contains iodine
o Complexes with helically-coiled polysaccharide chains (amylose of starch)
o Solution turns black or dark blue
 Testing water = control group

Part 2 – Lipids

 Fats, phospholipids, sterols

 Triglycerides: fatty acid + glycerol

Emulsion Test

 Tests lipids
o Non-polar compound
o Dissolve in ethanol
o Forms white precipitate
 Testing water = control group

Part 3 – Proteins

 Polymers of amino acids

o Amino group + carboxyl group + H atom + side group (R group)
 Chains of amino acids = polypeptides
o Forms polypeptide bonds

Biuret’s Test

 Tests polypeptides
 Reagent contains NaOH and CuSO4
o Copper ions react with peptide bonds
o Converts solution from blue to violet
  Free amino acids don’t react
o Don’t have polypeptides
o No reaction with peptide bonds
 Testing water = control group
 Testing albumin = positive control & standard for comparison

DNA isolation

 Meat tenderizer: enzyme that breaks down protein in DNA

 Stringy DNA
o DNA is long chain of nucleic acids
o So, long and thread-like
 Isolated DNA
o Water comes in contact with alcohol
o Becomes undissolved
o Clumps of DNA molecules
 Structural characteristics of DNA
o Rod has negative charge and DNA has positive charge
o DNA sticks to rod
 Not possible to spool out proteins
o DNA still suspended in solution
o Not long enough to adhere

Microscope and cells:

Part 1 – Microscope

 Magnification = ocular magnification (10x) * objective magnification

 Working distance: distance between slide and objective
 Finding field diameter
o 4x objective lens
o Position plastic ruler on millimeter division across diameter field of view
o Move ruler so that black lines are on extremities of field
o Measure diameter by counting number of lines
o Take measurement in micrometer
o 1mm = 1000 micrometer
 Inverse relationship between magnification and field diameter
o Mag i × FD i=Mag j × FD j
 Depth of focus is greatest on lowest power objective

Cheek cells & onion cells

 Use of t-Test
 Iodine used to stain the sample
o Makes structure easier to see

Cell Division

Part 1 – Mitosis
  Interphase
o G1: diploid number of chromosomes
o S: DNA replication
o G2: chromosomes composed of pair of chromatids
 Prophase
o Chromosomes start to condense
o Spindle apparatus forms.
o Nuclear envelope break down
 Metaphase
o Chromosomes line up at the metaphase plate, under tension from the spindle
o Sister chromatids of each chromosome are captured by microtubules from opposite spindle poles
 Anaphase
o Sister chromatids separate from one another and are pulled towards opposite poles of the cell
 Telophase
o Spindle disappears
o Nuclear envelope re-forms around each set of chromosomes
o Nucleolus reappears in each new nucleus
o Chromosomes start to decondense
 Cytokinesis
o Division of the cytoplasm to form two new cells

Part 2 – Meiosis

 Interphase
o G1: diploid number of chromosomes
o S: DNA replication
o G2: chromosomes composed of pair of chromatids
 Prophase 1
o Chromosomes start to condense
o Crossing over of homologous pairs
o Spindle apparatus forms.
o Nuclear envelope break down
 Metaphase
o Homologues line up at the metaphase plate, under tension from the spindle
 Anaphase
o Homologues separate from one another and are pulled towards opposite poles of the cell
o Sister chromatids remain attached to one another
 Telophase
 o Spindle disappears
o Nuclear envelope re-forms around each set of chromosomes
o Nucleolus reappears in each new nucleus
o Chromosomes start to decondense
 Cytokinesis
o Division of the cytoplasm to form two new cells
 Prophase
o Chromosomes start to condense
o Spindle apparatus forms.
o Nuclear envelope break down
 Metaphase
o Chromosomes line up at the metaphase plate, under tension from the spindle
o Sister chromatids of each chromosome are captured by microtubules from opposite spindle poles
 Anaphase
o Sister chromatids separate from one another and are pulled towards opposite poles of the cell
 Telophase
o Spindle disappears
o Nuclear envelope re-forms around each set of chromosomes
o Nucleolus reappears in each new nucleus
o Chromosomes start to decondense
 Cytokinesis
o Division of the cytoplasm to form four new cells

Oogenesis

 Follicle: sac or cavity surrounded by a layer of cells

 Begins in the female fetal ovaries during embryonic development
 Process starts with the oögonia (female germinal cells)
 Oögonial cells increase their cytoplasm to become diploid primary oocytes
 Meiosis occurs in all primary oocytes but stops at Prophase I of Meiosis I until puberty
 Female baby ovaries contain 2 million primary oocytes.
o At puberty, 400,000 primary oocytes remain in the ovaries
 At about 12 years of age, human female resumes meiosis once a month
 One primary oocyte per cycle completes meiosis I
 Gives rise to a large, functional, haploid secondary oöcyte and small non-functional polar body
 Polar body usually undergoes rapid degeneration
o Occasionally undergoes a second meiotic division to form two non-functional polar bodies
 Secondary oöcyte gives rise to an ovum and another polar body
 Cytokinesis in oögenesis is unequal
o Producing one large ovum and three small, non-functional polar bodies.
o Unequal cytokinesis that occurs has advantage of providing ovum with greater amount of cytoplasm
o Stored food than if an equal division were to occur
o Makes sure that the egg has enough materials to drive early divisions
o Feed rapidly dividing embryonic cells before more nutrients can be acquired through the placent.
 During menstrual cycle, as the follicle matures
o Becomes distended by an accumulation of fluid.
o Mature follicle, known as the Graafian follicle
o Moves outward to the surface of the ovary
 o First meiotic division is completed.
o Graafian follicle ruptures (ovulation)
o Secondary oöcyte leaves the ovary and is drawn into the fallopian tube
o Fertilization of the ovum can then occur within the fallopian tube
o Second meiotic division occurs only when a sperm cell comes in contact with it
o Gives rise to an ovum and a non-functional polar body
o Egg only fertilizable for a period of 24 hours after ovulation.
 Once ovulation has occurred, definite changes take place within the ovary
 Cells lining the ruptured follicle multiply and create a cell mass: corpus luteum.
 Temporary gland produces progesterone, which affects lining of the uterus: endometrium.
 If egg is not fertilized, corpus luteum degenerates
o Forms area of scar tissue known the corpus albicans.
o Because circulating levels of hormone decline with degeneration of corpus luteum, endometrium degenerates, and
bleeding results (menses).
 If egg is fertilized, implants into endometrium and begins embryological development
o Under influence of progesterone, endometrium becomes highly vascularized bed for the fertilized egg
o Implantation in uterine wall occurs 4–5 days after fertilization in fallopian tube

Spermatogenesis

 Male germinal cell: spermatogonium

 Undergoes mitosis to clone itself
 Undergoes meiosis to form sperm
 Spermatogenesis: process by which one spermatogonium develops into four spermatozoa (sperm)
 Adult male manufactures anywhere between 200–300 million sperm cells each day
 The sperm cells (spermatozoa) produced within seminiferous tubules of testes.
 Outer edge of the tubule: diploid epithelial spermatogonia that reproduce mitotically to maintain numbers.
 Some of the spermatogonial cells increase amount of cytoplasm becoming primary spermatocytes
o Undergo meiosis
 During first meiotic division, primary spermatocyte gives rise to two equal haploid secondary spermatocytes
 Secondary spermatocytes undergo second meiotic division giving rise to four equalled haploid spermatids
 Spermatids in turn mature (spermiogenesis) into spermatozoa by developing a flagellum
o Enzyme help penetrate the egg, acrosome and lots of mitochondria for energy
 Spermatids may be seen either in lumen or bordering it, usually associated with large sertoli cells.
o Sertoli cells play role in nourishing the spermatozoa
 In spaces between adjacent seminiferous tubules are clusters of cells called interstitial cells of Leydig
o Secrete testosterone, androgen, or male sex hormone.
 From start to finish, entire spermatogenic cycle in humans is 74 day
 Sperm may survive inside the female tract up to 72 hours

Evolution of You Lecture

 before evolution
o concept of evolution introduced until darwin 1859
o species never changed
o no extinction
 o no evolution
o for many people:
o the world as they saw it was how it had always been unchanging
 fossil record
o lack of physical evidence contributed to lack of undestaning
o only found a fraction of fossil record up until 1800
o no fossils of ancient humans
o only few stone tools found among extinct animals
o 1829: first fossil of hominid in engis belgium
o 1848: neanderthal skull
o 1856: bones in germany
o 1864: william king examine skull and proclaimed was a different species based on morphological characters of skull
o 1886: found well preserved neanderthal skeletons in Belgium
 diversity in homo
o homo habilis
 first species identified: homo genus (1960)
 habitat: africa
o homo erectus (1892)
 most successful human
 direct ancestor
 africa
o homo rudolfensis (1972)
 may be different variant of habilis
 not sure if different or related
o homo antecessor (1997)
 sister species to homo sapiens
 suggests another linear of human evolution
 wester and souther europe
o homo heidelbergensis (1907)
 ovelapped homo erectus
 believed to evolve from erectus
 asia, europe, africa
o denisovans
 sister species
 believed descended from ame immediate common ancestor
 no skull found yet
 skull found in 2021 called homo longi
 only human species identified on dna in 2010
o homo neanderthalensis (1864)
 sister species
 survives ice ages
o homo naledi
 lived alongside our own
 primitive (features adapted ti climbing trees)
 evidence that they buried their dead
 had very small brain cases but well developed areas of brain associated with intelligence in sapiens
 2015
o homo sapiens
 only extant species in homo genus
o homo floresiemsis (2003)
 lived alongside our own
 may have experienced insular dwarfism
 possibly evolved from erectus
o homo luzonensis (2019)
 luzon, philippines
 may have experienced insular drawfism
 progression of evolution
o straight line of evolution from ape ancestors to us
 dna
o half-life of 521 years
o dna too degraded to analyze
 ancient dna
o aDNA
o from 150 years to millions of years
o theoretical limit: 1.5 millions years
 how?
o PCR lets us amplify very tiny sample of DNA
o which regions of DNA are more likelh to break down over time
o can build ancient genomes from fragments by comparing them to modern ancestors
o can extract DNA from protected regions such as from inside teeth and bones
o can tell apart ancient dna from moden dna
 neanderthal project
o bacteria infiltrated DNA and contamined samples
o used computers models to detect and eliminate bacterial DNA
 discoveries
o neandethalensis started of 3000 individuals
 o had gene mutation in foxp2
o hybrdization with sapiens and producing fertile offspring
 denisovans
o interbred with neanderthals and sapiens
 ancestry
o genetic recombination
o lose some ancestor genes