Chapters 1 & 2: Evolution, Genetics, & Experience
Chapters 1 & 2: Evolution, Genetics, & Experience PSB2000
Popular in Introduction to Brain and Behavior
Popular in Natural Sciences
This 6 page Class Notes was uploaded by Sierra Gnecco on Thursday September 8, 2016. The Class Notes belongs to PSB2000 at Florida State University taught by Maria Greenwood in Fall 2016. Since its upload, it has received 108 views. For similar materials see Introduction to Brain and Behavior in Natural Sciences at Florida State University.
Reviews for Chapters 1 & 2: Evolution, Genetics, & Experience
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/08/16
PSB2000 Chapter 2 Evolution, Genetics, and Experience By Sierra Gnecco 2.1 : Thinking about the Biology of Behavior: From Dichotomies to Interactions ● We tend to think in dichotomies such as right-wrong, good-bad, attractive-unattractive, etc. ● Behavior in terms of dichotomies ○ Illustrated by two kinds of questions commonly asked about behavior: Is it physiological or psychological? Is it inherited or learned? Physiological or psychological? ● Why do wecall mental illness mental illness? ● Descarte argued that the universe is composed of two elements: ○ Physical matter which behaves according to the laws of nature. ○ Human mind (soul,self, or spirit), which obeys no natural law. ■ This belief is known as Cartesian dualism (human brain and mind are separate) 2 Inherited or learned? ● Nature vs. nurture ○ Do humans and other animals inherit their behavior or acquire them through learning? ○ Nature- behavior is due to genetics. ○ Nurture- behavior is due to environment. ● Aggressive behavior ○ Genetics -> environment -> behavior -> consequences influence physiological (including mental) state -> resulting behaviors 2.2 : Human Evolution ● Charles Darwin ○ Published O n the Origin of Species where he described his evolution theory- the most influential theory in the biological sciences. ○ He was the first to suggest that species evolve (undergo gradual orderly change) from preexisting species and the first to suggest how evolution occurs. ○ Had three kinds of evidence for his theory: ■ Evolution of fossil records via geological layers. ■ Similarity between species, suggesting they had evolved from a common ancestor. ■ Changes via selective breeding ○ Natural selection- the idea that heritable traits that are associated with high rates of survival and reproduction are preferentially passed on to future generations (ex: Galapagos Island finches) ○ Fitness- the ability of an organism to survive and contribute its genes to the next generation. 3 Evolution Evidence ● Galapagos Island- Darwin collected finches at Galapagos Island over the course of two years. They demonstrated natural selection. ○ 18 month drought -> seeds were large and difficult to eat for finches -> increase in beak size of one species of finch. Evolution & Behavior ● Behaviors play a role in evolution. Specific behaviors and physical features contribute to fitness and increases an animal’s ability to pass on its genes to future generations. Those behaviors include... ○ The ability to find food, avoid predation, and defend young. ■ Obvious role. ○ Social dominance and courtship displays. ■ Less obvious role. 2.3 : Fundamental Genetics ● Gregor Mendel ○ Studied dichotomous traits (Traits that occur in one form or another, never in combination / ex: seed color; every plant has either brown seeds or white) ● True-breeding lines- breeding lines in which interbred members always produce offspring with the same trait generation after generation. ● Dominant trait- an inherited characteristic that is determined by at least one dominant allele. ● Recessive trait- an inherited characteristic that is determined by two recessive alleles. ● Phenotype- an organism’s observable trait ● Genotype- a trait that can be passed on to an organism’s offspring through its genetic material. ● Gene- sequence of DNA. 4 ○ Contains information on hereditary characteristics such as height, hair color, eye color, etc. ● Allele- an alternative form of a gene. ● Homozygous vs. Heterozygous ○ Organisms that possess two identical genes for a trait are said to be homozygous. Ex: BB or bb ○ Organisms that possess two different genes for a trait are said to be heterozygous. Ex: Bb Chromosomes ● Chromosomes are in the nucleus of the cell and contain DNA. ● Sometimes genes overlap on a stretch of a chromosome. ● Chromosomes usually occur in matched pairs, and each species has a characteristic # of pairs in each of its body cells. ○ Humans have 23 pairs plus two sex chromosomes (XX female and XY male) ● Karyotype- the # and appearance of the chromosomes. Meiosis ● The process of cell division that produces gametes (egg cells and sperm cells). ○ Process: The chromosomes divide, and one chromosome of each pair goes to each of the two gametes. As a result, each gamete has half the usual # of chromosomes; and when a sperm cell and an egg cell combine during fertilization, a zygote (fertilized egg cell) is produced. 5 Chromosomes: Structure & Replication ● Each chromosome is a double-stranded molecule of DNA. Each strand is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose. ○ There are four nucleotide bases: adenine, thymine, guanine, and cytosine. ○ The sequences of these bases determine the genetic code. ● The two strands are coiled around each other and are bonded together by the attraction of adenine for thymine and guanine for cytosine. ● Replication ○ Process: The two strands of DNA unwind. Then the exposed nucleotide bases on each of the strands attract their complementary bases, which are floating in the nucleus’ fluid. Thus, when the unwinding is complete, two double-stranded DNA molecules identical to the original are created. ■ Errors in the process can lead to mutations. For example, an extra chromosome in each cell leads to Down Syndrome. Sex Chromosomes & Sex-linked Traits ● Autosomal chromosomes- chromosome that come in matched pairs; in mammals, all of the chromosomes except the sex chromosomes are autosomal. ● Sex chromosomes- the pair of chromosomes that determines an individual’s sex. ● Sex-linked traits- traits influenced by genes on the sex chromosomes. ● Consider a gene on the X chromosome… ○ If a male gets this gene, he will display the trait. ○ A female must get it on both of her X chromosomes in order to display the trait. ○ If a female has it only on one of her X chromosomes, she is a carrier. ● Examples of sex-linked genes: homophilia, red-green colorblindness, Fragile X Syndrome, and Duchenne muscular dystrophy. Sex-limited Genes ● Present in both sexes but only has an effect on one. ○ EX: Genes for facial hair (men), milk production (women), horns, color patterns, etc. 6 ● On autosomal chromosomes and are turned on under the influence of sex hormones. Structure of DNA ● Double stranded molecule (helical model) ● Four base pairs ● Self-replicating ● Codon- 3 base pairs which code for an amino acid. ● Transcription- DNA -> RNA ● Translation- RNA -> protein Genetic Code & Gene Expression ● Proteins- long chains of amino acids that control the physiological activities of cells. ○ Important components of cellular structure. ● Enhancers- stretches of DNA whose function is to determine whether particular structural genes initiate the synthesis of proteins and at what rate. ○ The control of gene expression by enhancers is a vital process because it determines how a cell will develop and how it will function once it reaches maturity. ● Transcription factors- proteins that bind to DNA and influence the extent to which genes are expressed. ● The expression of a structural gene ○ Process: (1) DNA molecule unravels, exposes gene to be expressed. (2) Transcription- a strand of RNA is copied from one of the strands of exposed DNA -> RNA goes to cytoplasm. (3) ranslation- Messenger RNA attaches to a ribosome -> ribosome reads each codon and attaches appropriate amino acid. (4) Ribosome reaches end of RNA, codon instructs release of “completed” protein. Epigenetics ● Epigenetics- the study of all mechanisms of inheritance other than the genetic code and its expression.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'