ANT 230 - EXAM 1
What did Darwin actually do?
"On the Origin of Species" Two great realizations: (1) All life on Earth is related through common ancestry, and more related organisms share a more recent common ancestor (2) The mechanism for evolutionary change is natural selection
Rosalind Franklin
(1953) James Watson and Francis Crick, using detailed microscopic images, taken by Rosalind Franklin, discovered the structure of DNA and did not give her credit for it.
Multiple codons code for the same amino acid
(ex:) "Glycine (Gly) is represented by four different codons (GGT, GGC, GGA, GGG)" The reason for this is to avoid negative consequences from mutations If a mutation occurs due to one base being substituted for another, there is a good chance that the codon will result in the same amino acid If not, the change of an amino acid could cause major issues in the ultimate protein
DNA is made of three things
1) A type of sugar 2) Phosphate group 3 Nucleotide base pair The sugar and phosphate form the backbone of the long DNA molecule and do not vary along the chain What varies along the chain are the nucleotide base pairs (A, T, G, C)
Karyotype
A display of the chromosome pairs of a cell arranged by size and shape.
(In DNA) Nucleotide base pairs do not randomly cling to each other
A only clings to T, and C only clings to G (called complementary bases) This means that if you know one side of the DNA chain, you know the other. (ex:) "One side is CAT other side must be GTA"
Cells are the basic units of life in all living organisms
All animals, plants, fungi, and many single-celled organisms called protists are made of eukaryotic cells
Regulatory have allowed us to understand major evolutionary events (more)
All baby mammals have the ability to digest milk (because of this they produce the enzyme called lactase). Some humans have lactase persistence (genes are not turned off and can continue to digest milk as adults) while others have lactose intolerance. Natural selection can act as on the products of structural genes and it can also operate on the products of variation in regulatory genes Research on human and chimpanzee research (Although our structural genes are very similar, there are important differences in regulatory genes)
Domestic Dogs
All domestic dogs share a common ancestor, the wolf The extreme variation exhibited by dog breeds today has been achieved in a relatively short time through artificial selection This variability is due to humans selecting for individuals with favorable traits to pass on their genes to the next generation, called artificial selection (humans become the selective pressure instead of it only being the environment)
Allele
Alternative forms of a gene (ex:) "If a gene determines the height of a pea plant, the different allele would determine whether the plants are tall or short"
SNPs ("snips")
Although any two humans may have over 99% of their DNA base pair order, there are differences known as SNPs (short for single nucleotide polymorphism) Vary from individual to individual (can be used to solve crimes using DNA)
Homeobox Genes (Hox genes)
An evolutionarily ancient family of regulatory genes (highly conserved) that directs the development of the overall body plan and the segmentation of body tissues These are the master switches that determine the general form of an animal's body
Mitochondria
Are the site of mitochondria (mitochondrion, singular) that generate most of the chemical energy needed to power the cell's biochemical reactions
Transcription
The DNA is unwound, or unzipped by enzymes. (Unlike replication) only one strand of DNA is used during transcription and only a specific section of the DNA is unwound - this region is called a gene . The unwound DNA strand serves as a template for making a single-strand molecule of messenger RNA Once the gene is fully transcribed, the messenger RNA molecule leaves the nucleus and finds ribosomes in the cytoplasm of the cell
How does DNA work?
The DNA molecule is wound up into compact structures that we have already encountered: chromosomes. Sections of that DNA "code" for specific proteins your body makes and needs (these sections of DNA are called genes) All the genes put together in all the chromosomes are called the genome The DNA that is in the nucleus of our cells is called homoplastic, meaning that it is more or less the same in every cell in our body
Mitosis (After chromosome duplication)
The cells technically have 92 chromosomes, which all line up in the middle of the cells so that one full set is on one side and another full set is on the other side of the cell midline The cell pulls apart into daughter cells, each with identical DNA The microscopic image is of skin cells dividing into daughter cells. Each of these cells has 23 pairs of homologous chromosomes (46 total) https://uk.instructure.com/courses/1990558/modules/items/24806133
Allopatric speciation
The formation of new species in populations that are geographically isolated from one another.
Protein Synthesis: Problems
The genetic code is in the DNA The DNA is found only in the nucleus The ribosomes are responsible for forming proteins The ribosomes are found in the cytoplasm
Genotype
The genetic makeup of an individual: (Genotype can refer to an organism's entire genetic makeup or to the alleles at a particular locus) (ex:) "TT, Tt, tt"
Right before the final cell divides in meiosis
The homologous chromosomes can recombine their chromosomes in a process called crossing over A chunk of chromosome (2 from the mother's line) can switch with a chunk of chromosome (2 from the father's line). So the 23 chromosomes in the gametes are not only a random assortment of chromosomes from the mother and from the father - within each chromosome, there will be a combination of genes from the individual's mother and father. Genes that are close together on a chromosome therefore tend to move together a cluster together (these clustered are called haplotypes - can be used to assess the history of genetic lineages)
Chromosomes
The molecules under which DNA is organized into Made of condensed, coiled DNA wrapped around proteins called histones. DNA is usually uncoiled in long threads throughout the nucleus These DNA strands coil and shorten prior to cell division to form chromosomes (during normal cell functions, chromosomes exist as single-stranded structures)
Translation (part II)
The next three nucleotides in the codon are AGU, which match with the anticodon UCA, which is attached to the amino acid serine. ^ This goes on and on, in groups of three, until the last codon (UAG), which is the stop sequence. The amino acid chain is then released into the cytoplasm. It folds into a three-dimensional structure (or bonds with other 3D proteins) which gives these proteins their specific properties
Mitochondrial DNA (mtDNA)
The nucleus is not the only part of a cell that contains DNA Mitochondrial DNA (mtDNA) is much smaller (it contains only 37 genes) These genes are inherited only from your mother, meaning that they can be used to trace one's maternal lineage (matriline)
Phenotype
The observable or detectable physical characteristics of an organism; the detectable expressions of genotypes, frequently influenced by environment How genes are expressed: (ex:) "Tall or short"
Locus
The position on a chromosome where a given gene occurs. The term is sometimes used interchangeably with gene
Protein Synthesis
The process by which a DNA code is turned into a chain of amino acids acids, occurs in cells
Genetics
The study of gene structure and action, and the patterns of inheritance of traits from parents to offspring Genetic mechanisms are the foundation for evolutionary change
What is anthropology?
The study of human culture and evolutionary aspect of human biology
Evolution: Scientific Theory
The theory has been tested and subjected to verification through accumulated evidence (and has not been disproved). Science is a self-correcting process The theory of evolution has been supported by a mounting body of genetic evidence. The theory has stood the test of time and continues to grow
Compare Darwin's explanation of evolution to Lamarck's giraffe example
There is variation in an ancient giraffe population, with some individuals having longer necks than others. They feed on high branches. Those with longer necks eat, survive, reproduce, and pass on the trait of a long neck to the next generation. Those with shorter necks cannot reach as much food, are weak, and may even starve to death. The frequency of of long-necked individuals in the population increases over time
Proteins
They are what bodies are made of Are critical for normal functioning of an organism
How do we go from a DNA molecule to a human?
Think of the bases as letters of an alphabet A sequence of three bases is a codon, which you can think of as words (each codon codes for an amino acid) When amino acids are strung together, they form a protein Genes are the segments of DNA that code for a product, such as a protein
Punnet Square
This shows the next step in Mendel's experiment: He bred the Tall (Tt) plants together. (1) One will have a BIG T from the mother plant and a BIG T from the father plant (circled in red) (2) Two plants will have a mixture of alleles: one BIG T and one little t (circled in blue) (3) One plant will have two little alleles (circled in green)
Dominant
Traits are governed by an allele that can be expressed in the presence of another, different allele Dominant alleles prevent the expression of recessive alleles in heterozygotes
Recessive
Traits are not expressed in heterozygotes For a recessive allele to be expressed, there must be two copies of the allele
Zygote
Union of cells to form the potential of developing into a new individual When they (egg and sperm cells) fuse together during conception, the chromosomes can be added together to form 46 (the number found in somatic cells)
RNA Coding
Uses A, G, C, and U U stands for uracil and it binds to A (just like T does in DNA coding)
Biocultural approach to anthropology
Using all of the aforementioned approaches
Protein Synthesis: Transcription and Translation Video
https://uk.instructure.com/courses/1990558/modules/items/24806132
DNA Replication
Because our cells are alway reproducing themselves, the DNA needs to be able to reproduce itself as well DNA molecule basically unzips itself and each half of the DNA strand serves as a template (one double helix of DNA can actually be turned into two https://util.wwnorton.com/jwplayer?type=video&msrc=/wwnorton.college.protected/coursepacks/phys_anthro/animations/animation_dna_replication.mp4&isrc=/wwnorton.college.protected/coursepacks/phys_anthro/animations/animation_dna_replication.jpg&csrc=/wwnorton.college.protected/coursepacks/phys_anthro/animations/animation_dna_replication.vtt&cp=1
Amino Acids and Protein
Besides replicating itself, the other critically important thing DNA does is code for proteins
Why does the Anthropological Perspective matter?
By learning about cultures other than our own, we can avoid an ethnocentric view of other cultures (meaning that we do not view any one cultural perspective above any other).
Somatic cells
Cellular components of body tissues such as muscle, bone, skin, nerve, heart, and brain (also called body cells) Contain a complete copy of the organism's DNA (ex: "In humans, somatic cells have all the DNA packed in 46 chromosomes) They can also replicated through mitosis
"Descent with modification"
Darwin surmised that birds with certain physical features, those that allowed them to eat certain foods in their environment, survived and reproduced. Through reproduction, they could pass on these physical features to their offspring, thus increasing the frequency of these features in the overall population of birds. Also adapt to their environment Natural selection is the driver of evolution
Regulatory Genes (Can be thought of as on/off or dimmer switches)
Determine if a gene is on or off, and regulate the amount of protein produced and when (ex:) If the genes controlling connective tissue growth are left on a bit longer during development, it can result in longer, thinner fingers (among other traits)
Jean-Baptiste Lamarck (1744-1829)
Developed a theory to explain the evolutionary process, known as the inheritance of acquired characteristics (Lamarck's giraffes) ^ the idea that living organisms have changed over time was already around before Darwin came along
Sex chromosomes (1 pair)
Females of two X's and Males have an X and a Y One inherited from mother and one inherited from father (male determines sex since mother can only contribute an X chromosome) Because the male has both an X and a Y, there is a 50-50 chance that a sperm will contain an X or a Y
Protein Synthesis: Transcription and Translation
First, the DNA code is read by enzymes, producing a molecule called messenger RNA This process, in which the messenger RNA is created from a DNA code is called transcription The messenger RNA then leaves the nucleus of the cell and enters the cytoplasm. It binds to the ribosomes, which are organelles that facilitate the translation of messenger RNA into a chain of amino acids, which ultimately form a protein.
John/Charles Edmonstone
Formerly enslaved man from present day Guyana who taught taxidermy at the University of Edinburgh, where Darwin went to school. His accounts of the tropical rain forests in South America likely inspired Darwin to seek out the opportunity on the HMS Beagle
John Ray (1627-1705) and the species concept
Introduced the biological species concept To him, species were groups of organisms that were able to reproduce with one another Two groups of organisms that could not reproduce with one another were not considered the same species
DNA Structure
Is composed of two chains of nucleotides, comprising a double strand or double helix Cellular function and an organism's inheritance depends on the structure of and function of DNA
Thoughts on Inheritance During Darwin's time
It was thought that offspring were a 50-50 blend of their parents (blending inheritance), which complicated his theory (since variation is a fundamental tenet of natural selection)
similarities and differences between meiosis and mitosis
Meiosis starts the same way as mitosis (the DNA replicates and the homologous pair up. The cells then divide into two identical daughter cells) Unlike mitosis, the cells then divide again, resulting in four daughter cells with 23 chromosomes each, but no pairs.
Results when one trait (height) is considered at a time
Mendel bred one of his purely tall plants with one of his purely short plants According to the ideas of blending inheritance, all of the offspring should be intermediate or medium in height. He found that all of the offspring in the second generation (F1 generation) were tall. Next he bred the tall offspring with each other. While most (75%) of the next generation (F2 generation) were tall, surprisingly 25% of the offspring were short (the short plants had reappeared)
Mitosis (Start)
Mitosis starts with a single diploid cell that has 23 pairs of homologous chromosomes (or 46 chromosomes) These chromosomes duplicate by unwinding their DNA and attaching free nucleotide bases to the template strands in the manner already discussed
Nucleic Acids
Molecules that contain genetic information that controls the cell's function DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)
Culture
Strategies humans use to adapt to their environment (Technologies, subsistence patterns, housing types, clothing, religion, marriage/family, values, and gender roles)
Eukaryotic cells
Structurally complex cells (appeared 1.2 billion years ago)
1) Cultural anthropology
Study global patterns of belief and behavior found in modern and historical cultures. Their research results in ethnographies, which are detailed descriptive studies of human societies.
3) Linguistic anthropology
Study language and its impact on society
4) Physical/Biological anthropology
Study of human biology, both past and present, to better understand human origins, human evolution, and human biological variation Uses the framework of evolution with an emphasis on the interaction between biology and culture
2) Archeology
Study past cultures and lifeways through scientific recovery, analysis, and interpretation of material remains of past societies (or artifacts).
Thinking of DNA as a ladder
Sugar and phosphates = the uprights Nucleotide base pairs = the rungs (The rungs are made of two base pairs that cling together using hydrogen bonds)
Alfred Russell Wallace (1823-1913)
Suggested species descended from other species and new species were influenced by environmental factors Had similar ideas as Darwin but in a completely different part of the world (Indonesian archipelago) Presented joint paper, coauthored with Darwin on evolution and natural selection (to the Linnean Society of London in 1858) The fact that two scientists, working independently came up with the same mechanism for evolution is robust evidence that natural selection is a powerful tool for explaining the pattern of life
Carolus Linnaeus (1701-1778) and Taxonomy and binomial nomenclature
Sweedish naturalist who devised a system for naming and classifying all living organisms Still used today and allows scientists from all over the world, speaking different languages, to understand one another. Proposed that each species should receive a unique name composed of a genus and a species (ex:) "Humans = Homo sapiens; Chimpanzees = troglodytes" This system revealed that humans are clustered in distinct way (which could only be explained by sharing a common ancestor)
The basic processes of Natural Selection
1) All species are capable of producing offspring at a faster rate than food supplies increase (limited resources) 2) There is biological variation with all species 3) Since in each generation, more individuals are produced than can survive, and because of limited resources, there is competition among individuals 4) Survival of the "fittest" a. Individuals possessing favorable variations or traits ("speed, resistance to disease, protective coloration) have an advantage over those who do not b. Fitness: is a measure of relative reproductive success of individuals and is measured by an individual's genetic contribution to the next generation compared to that of other individuals (In other words, an individual will have greater "fitness" because favorable traits increase the likelihood of survival and reproduction) 5) The environmental context determines whether or not a trait is beneficial. Hence favorable traits become most advantageous are the results of a natural process. These are considered selective pressures 6) Traits are inherited and passed on to the next generation. Individuals who produce more offspring are said to have a greater reproductive success, or fitness 7) Variations accumulate over long periods of time time, so later generations may be distinct from ancestral ones 8) As populations respond to pressure over time, they may become distinct species, descended from a common ancestor. This is called speciation
Precursors to the Theory of Evolution
1) Charles Lyll (1797-1875) and Uniformitarianism 2) Georges Cuvier (1769-1832) + Mary Anning (1799-1847) Extinction and Catastrophism 3) Carolus Linnaeus (1701-1778) and Taxonomy and binomial nomenclature 4) John Ray (1627-1705) and the species concept 5) Thomas Malthus (1766-1834) and the limits to population growth 6) Jean-Baptiste Lamarck (1744-1829)
4 branches of anthropology
1) Cultural anthropology 2) Archeology 3) Linguistic anthropology 4) Physical/Biological anthropology (Also) Applied/ Forensic anthropology
Emerging scientific views before Darwin
1) Earth is old 2) Earth's surface has changed over time 3) Plants and animals have changed
Common views before Darwin
1) Earth is young 2) Fixity of Species (Notion that species, once created, can never change)
Darwin's inspirations
1) From Lyell (Earth is old; gradualism) 2) From Cuvier and Anning (Fossils resemble living forms; extinction) 3) From Malthus (Ideas about reproduction, populations, and variation) 4) From linnaeus and Lamarck (Species related through common ancestry; species can change)
There are two types of eukaryotic cells in all animals and plants
1) Somatic cells 2) Gametes
Mitosis: Prenatal Development
1) You started as a single fertilized egg (called a zygote) which had 46 chromosomes. a. During embryological development, the little zygote divides to form 2, 4, 8, 16, 32, 64, until eventually trillions of cells b. These cells soon form tissues and organs c. Every cell contains 46 chromosomes d. Embryological development occurs because DNA can replicate itself (so that the cell goes from 46 chromosomes to 92 before dividing into 2 cells, each with 46 chromosomes). This process is called mitosis 2) Cells with this full set of chromosomes (46) are called diploid 3) Cells with half the number of chromosomes (23) are called haploid (These are the egg and sperm cells)
Out of the thousands of plants Mendel bred he always found the ratio was...
25% two dominant BIG alleles, 50% mixed alleles, and 25% two recessive little alles *Mendel could not see the alleles themselves; all he could see was their effect on the organism https://uk.instructure.com/courses/1990558/modules/items/24806142
Meiosis (Background info)
Gametes have to divide up the DNA a bit differently than somatic cells do (if an egg cell has 46 chromosomes and a sperm had 46 chromosomes, the resulting zygote would have 92 and this simply would not work) Instead of having a full copy of the organism's DNA, gametes are haploid, meaning they only contain one chromosome for each pair. The one chromosome can be the one inherited from the mother or the one inherited from the father. With 23 chromosomes, the number of different combinations is exceptionally high, meaning that each egg and each sperm cell contains a unique combination of genes from the organism's mother and father (introducing yet more potential for variation)
Regulatory Genes
Genes that code for the production of proteins that can bind to DNA and modify the actions of genes Many are active only during certain stages of development
Heterozygous
Having different alleles at the same locus on members of a pair of chromosomes (ex:) "Tt"
Homozygous
Having the same allele at the same locus on both members of a pair of chromosomes (ex:) "TT or tt"
If Darwin did not "invent evolution" then why is he so famous?
He proposed a mechanism for how species change over time: natural selection
Gregor Mendel (1822-1884)
His work illustrates basic laws of inheritance (discredited blending inheritance) He discovered that traits were inherited discreetly, through units called genes These genes come in different versions called alleles Often one version could exert dominance over another version that would be called recessive
Chromosome Types
Homologous pairs; 23 total pairs 23 of these chromosomes were inherited from the mother and 23 from the father and each chromosome number (1 to 23) is different in its lengths and in the genes it contains The chromosomes pair up into matching, or homologous, pairings in the somatic cells 1) Autosomes (22 pairs), Sex chromosomes (1 pair)
Notice that whether you are a human, a mouse, or a fruit fly, heads are where they should be, bodies are where bodies should be, and limbs are where limbs should be. Why is this?
Hox genes regulate the position of the major body parts during embryological development Small changes in how long these genes are switched on, or where they are expressed, can result in overall body form. (ex:) "The genes for the neck region are positioned differently in birds and snakes, giving birds long necks and snakes short necks (but long bodies). (ex:) "The Hox genes that determine forelimb and finger length are switched on for a longer period of development in bats compared to other mammals" Selection can favor the products of variation in regulatory genes as effectively as structural genes
More meiosis
If chunks of DNA are exchanged on nonhomologous chromosomes (called translocations), diseases such as leukemia can result If the Chromosomes fail to divide, the resulting gametes can have too few or too many chromosomes Too few can result in a monosomy and too many in a trisomy (down syndrome is an example of a trisomy, in which there are three rather than two copies of chromosome 21) https://uk.instructure.com/courses/1990558/modules/items/24806134
Genetic Code (codons)
Nucleic acids exist exist in all living organisms (the language is always the same) The table shows the amino acid that each codon codes for Codons code for "punctuation" (a "stop" codon tells the cells that the sequence of amino acids is complete)
Translation
Once messenger RNA binds to a ribosome, translation of the code into amino acids can begin (three nucleotides called a codon are read by the ribosome by matching a complementary anticodon to the codon) (ex:) " If the messenger RNA codon is AUG, then the anticodon has to be UAC" - since those are the three nucleotides that are complementary to the codon ^ It is important to note that these anticodons are attached to a very specific amino acid (methionine, in this case) in a structure called a transfer RNA (tRNA)
Translation only occurs in a small percentage of the human genome
Only about 5% of the total genome is composed of structural genes that code for proteins Much of the rest of the genome was once regarded as "junk DNA" We now know that much of this "junk DNA" is composed of regulatory genes, which turn genes on and off
Subfields of Biological Anthropology
Paleoanthropology, Human variation, molecular anthropology, human osteology, bioarcheology, paleopathology, forensic anthropology, primatology
Regulatory have allowed us to understand major evolutionary events
Paleontological evidence demonstrates that modern birds evolved from a group of feathered dinosaurs. Dinosaurs had teeth but birds do not. Scientists have recently discovered that birds still have the structural gene to make teeth, but the regulatory genes controlling those structural genes have been turned off. Human body and hair (humans have less body than other primates). We still have the genes for full body hair coverage but these genes have been down regulated
The Scientific Method: How we know what we know
Process of explaining natural phenomena by means of observation, developing explanations, or hypotheses. It is a self-correcting process.
How does DNA code for proteins?
Proteins are made by amino acids (there are 20 different kinds of amino acids) Humans can manufacture 12 of these; the other 8 have to be eaten and are therefore called essential amino acids These 20 different amino acids can combine into chains of various lengths and different proportions These properties are what makes a protein like keratin different from a protein like hemoglobin
Gametes
Sex cells involved in reproduction and not important as structural components of the body These gametes contain only half of the organism's DNA (23 chromosomes in humans) and replicate through meiosis. (Egg cells produced in female ovaries) (Sperm cells produced in male testes) Zygote
Sex does not equal gender in humans
Sex refers to biological differences between males and females based on physiological differences (sex chromosomes, reproductive organs, hormones, secondary characteristics) Gender is a part of a person's social identity. It is based, in part, on the cultural construction of beliefs and behaviors considered appropriate (neither sex or gender is binary) Gender categories and the roles that males and females plays differ among societies
Lamarck's giraffes
Shown to be incorrect Giraffes once had a short-necked ancestor. In order to reach higher and higher branches, giraffes stretched their necks. Adult giraffes who have stretched out their necks will pass on this acquired feature of a long neck to their offspring Over time, necks get longer and longer in the giraffe lineage.
Autosomes (22 pairs)
Since one chromosome was inherited from the mother and the other from the father, 22 of the 23 homologous pairs are referred to as autosomes The 23rd pair determines the sex of the individual
Codominance
Sometimes, neither allele that is chemically different dominates the other (ex:) "ABO blood group"
Adaptive radiation
The 13 different finch species that currently live on the Galapagos is a kind of rapid and prolific speciation known as an adaptive radiation
Darwin's voyage on the HMS Beagle (1831)
The Beagle sailed from England, around the tip of South America, to the Galapagos Islands, around the southern coast of Australia and Africa, and back to England Noticed that different kinds of birds, finches in particular, were quite variable and different kinds of finches lived on different islands. Their variation was not random as it appeared to vary according to the habitat in which they lived (they adopted for very specific environments)
Thomas Malthus (1766-1834) and the limits to population growth
Wrote "An Essay on the Principle of Population" (Laid the foundation for many of Darwin's ideas in natural selection) Argued that population growth could be exponential, resulting in billions and billions of humans in a short period of time. Observed that the population of humans grows more slowly than expected because there is not enough food for everyone (populations are limited by resources and there is a struggle for existence, with only certain individuals surviving and reproducing)
