20230407 Eva Bio Lesson 2

The related organisms have died out

Different clades

Convergence (different ancestor) may occur

Divergence: common ancestor + different structures

DNA base sequence

Species with the most similar DNA base sequence are more closely related

A base substitution from GAG to GTG causes a change of codon on mRNA from GAG to GUG

This causes a wrong complementary anticodon on tRNA with another corresponding amino acid

Glutamic acid is replaced by valine

This distorts the hemoglobin protein's structure, producing Hb^s and leading to a change in red blood cell's shape

As Hb^s cannot carry enought O₂, it causes fatigue

Also, sickled-shaped blood cells might block the cpillaries and causes tissue damage and pain

Antibiotic resistance exists as a genetic variation

Antibiotic resistance may occur from transfer of genetic material

Resistance specific gene reproduce only in the presence of antibiotic

Frequency of resistant bacteria increases in population

Resistant population replaces non resistant overtime

Variation is different phenotypes (differences between inividuals in a population)

Struggle/competition for survival

Some individuals have advantageous characteristics/are better adapted/have greater chance of survival/reproduction than others

Favorable alleles (genetic variations) passed on/inherited by offspring/next generation

Divided species/gene pool/ part of species/ gene pool become separated/species splits into separate populations

Reproductive isolation/lack of interbreeding

may be due to temporal/behavioral/geographic isolation

different natural selection/different selective pressures

A: gills/fins/scales/no limbs/external fertilization

B: homeothermic/warm-blooded/endothermic/lungs/tetrapod/four limbs/pentadactyl limbs/internal fertilization

C: hair/fur/mammary glands/milk