Week 4: What Is Evolution, Exactly? (Lecture 4) Flashcards
define evolution
descent with modification
what exactly is being modified over time
we are measuring changes in traits
what are traits
Characteristics or attributes of an organism that are
expressed by genes and/or influenced by the environment.
give examples of physical traits
hair colour, leaf shape, size at maturity, etc.
give examples of behavioural traits
care invested in offspring, mating behaviours, foraging (food search) methods, etc.
what are some key common traits that all mammal possess
“Warm blooded” – use metabolism to regulate their own temperature.
Give birth to live young (no externally laid eggs)
Nurse young with mother’s milk
They originated (first evolved) on land!
compare and contrast the Traits:
Cetaceans vs. Fish
Cetaceans vs. Fish
Ceteceans (dolphins):
* Streamlined
* Powerful tails
* Up and down movement
* Blowhole draws in air for oxygen extraction
* Long muscles run the length of their bodies
* Birth live young
* Feed young with mammary glands
Fish (tuna):
* Streamlined
* Powerful tails
* Side to side movement
* Gills pump in water for oxygen extraction
* Short sets of muscles form vertical blocks
* Births vary
* No mammary glands
Similartities
* streamlined
* powerful tails
Pakicetus
Earliest cetacean, first terrestrial whale known
Lived 50 million years ago
lived during the Eocene epoch, approximately 50 million years ago.
Ambulocetus
One of the earliest whales
Lived 47- 49 million years ago
Short legs and massive feet
describe whale evolution
Moved from strictly terrestrial to partially, and then to fully aquatic.
Traded nostrils for a blowhole on the top of the head.
Lost their legs and fur.
True or False: Dolphins actually
develop legs as embyros.
True
True or False: All of life on earth is the product of evolution from one common ancestor.
True
what is the tree of life
Traces the history of life on Earth
A phylogenetic tree based on rRNA data, emphasizing the separation of bacteria, archaea, and eukaryotes, as proposed by Carl Woese
list the 5 Fundamental principles of evolution
A. Organisms inherit traits from their ancestors
B. These traits are passed on in the form of DNA
molecules
C. Cells use DNA as a recipe book for building proteins and other organic molecules
D. New copies of DNA are made for offspring
E. Mistakes in copying are called mutations
F. Mutations may be harmful, neutral, or beneficial… most mutations are neutral, or harmful.
how do genes lead to traits
Genetic Information in DNA: Genes are segments of DNA (deoxyribonucleic acid) that contain the instructions for building and operating an organism. DNA is a double-stranded molecule composed of four nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
Transcription: The process begins with transcription, during which a gene’s information is transcribed from DNA into a complementary molecule called messenger RNA (mRNA). This occurs in the cell’s nucleus.
RNA Processing: The newly transcribed mRNA may undergo further processing, such as the removal of introns and the addition of a protective cap and a poly-A tail.
Translation: The processed mRNA leaves the nucleus and enters the cell’s cytoplasm, where it binds to ribosomes. Ribosomes read the mRNA’s instructions in sets of three nucleotide bases called codons and match them to specific amino acids.
Amino Acid Sequence: Amino acids are the building blocks of proteins. As the ribosome reads the mRNA, it links amino acids together in a specific sequence, forming a polypeptide chain.
Protein Folding: The polypeptide chain then folds into a three-dimensional shape, driven by the interactions between its constituent amino acids. This folded protein’s shape determines its function.
Protein Function: Proteins are diverse molecules with various functions in the body. Some proteins are enzymes that catalyze chemical reactions, while others are structural proteins, hormones, antibodies, or transport molecules. The specific functions of proteins are essential for various biological processes and traits.
Influence on Traits: Traits are characteristics or attributes of an organism, such as eye color, height, or the ability to taste a particular substance. These traits are often determined by the specific proteins produced as a result of gene expression. For example, the gene responsible for eye color encodes a protein that determines the amount and type of pigment in the eye’s iris.
Genetic Variation: Different versions of genes, called alleles, can result in variations of traits within a population. For instance, multiple alleles of the gene responsible for hair color lead to the wide range of hair colors seen in humans.
