Podcast Beta
Questions and Answers
What is the key implication of Mendel's discovery that the offspring from the second cross have a 25% chance of having white seeds?
What is the term for the process of cell division that produces gametes with half the usual number of chromosomes?
What is the role of activators in gene expression?
What is the term for the study of heritable changes in gene function that occur without a change in the DNA sequence?
Signup and view all the answers
What is the term for the process of creating a new DNA molecule from an existing DNA molecule?
Signup and view all the answers
What is the term for the sequence of three nucleotide bases that instructs the ribosome to add a specific amino acid to a protein?
Signup and view all the answers
What is the main contribution of the Human Genome Project?
Signup and view all the answers
What is the term for the process by which chromosomes exchange genetic material?
Signup and view all the answers
What is the term for the type of RNA that carries the genetic code out of the nucleus of the cell?
Signup and view all the answers
What is the term for the process of converting the genetic code from DNA into a sequence of amino acids?
Signup and view all the answers
What percentage of human DNA contains protein-encoding genes?
Signup and view all the answers
What is the term for the study of the development of an individual through their lifespan?
Signup and view all the answers
What is the process by which a methyl group attaches to a DNA molecule, usually at Cytosine sites, in mammals?
Signup and view all the answers
What is the term for the catalogue of all the modifications to DNA within a particular cell type, other than changes to the nucleotide base sequence?
Signup and view all the answers
What is the term for the modifications of RNA that occur after transcription, but do not involve changes to the RNA base sequence?
Signup and view all the answers
What is the process by which histones change their shape, affecting the shape of an adjacent DNA?
Signup and view all the answers
What is the percentage of RNA molecules that are of the large protein-encoding variety?
Signup and view all the answers
What is the term for the transmission of experiences via epigenetic mechanisms across generations?
Signup and view all the answers
What is the term for the study of the mechanisms that influence the expression of genes without changing the genes themselves?
Signup and view all the answers
What is the term for the development of a species through the ages?
Signup and view all the answers
What is the primary concern regarding psychosurgery?
Signup and view all the answers
What is the term used to describe the general intellectual climate of our culture?
Signup and view all the answers
What is the primary flaw in thinking about the biology of behavior in terms of traditional physiological-psychological and nature-nurture dichotomies?
Signup and view all the answers
What is the term used to describe a simple way of thinking, such as good-bad or right-wrong?
Signup and view all the answers
Why were patients often judged as improved after undergoing psychosurgery?
Signup and view all the answers
What was the primary issue with Moniz and others' evaluation of psychosurgery?
Signup and view all the answers
What is the primary problem with impressions that the operation was therapeutically effective?
Signup and view all the answers
What is the primary goal of describing the origins of the physiological-psychological and nature-nurture ways of thinking?
Signup and view all the answers
Study Notes
Mendelian Genetics
- Gregor Mendel, an Augustinian monk, studied dichotomous traits in true-breeding lines of pea plants.
- Dichotomous traits are characteristics that occur in one form or another, never in combination.
- True-breeding lines are interbred members that always produce offspring with the same trait generation after generation.
- Mendel's key findings: when true-bred brown and white peas are crossed, all offspring from the first cross have brown seeds, whereas 25% of offspring from the second cross have white seeds.
- Dominant trait: appears in 100% of first-generation offspring.
- Recessive trait: appears in 25% of second-generation offspring.
- Phenotype: an organism's observable traits.
- Genotype: genetic traits passed on to offspring.
Mendel's Theory
- 2 kinds of inherited factors for each dichotomous trait.
- Each inherited factor is called a gene.
- Each organism possesses 2 genes for each of its dichotomous traits.
- 2 genes that control the same trait are called alleles.
- Homozygous: organisms that possess 2 identical alleles.
- Heterozygous: organisms that possess different alleles.
- One of the 2 kinds of genes for each dichotomous trait dominates the other in heterozygous organisms.
Chromosomes
- Chromosomes: threadlike structures in the nucleus of each cell.
- Chromosomes occur in matched pairs in all multicellular organisms.
- Humans have 23 pairs of chromosomes, with an allele on each chromosome.
- Meiosis: the process of cell division that produces gametes (egg and sperm cells).
- Genetic recombination: crossover of chromosomes to exchange genetic material.
- Mitosis: all other cell division in the body.
Structure and Replication
- Each chromosome is a double-stranded molecule of deoxyribonucleic acid (DNA).
- Each strand is a sequence of nucleotide bases attached to a chain of phosphate and deoxyribose.
- 4 nucleic bases: adenine, thymine, guanine, cytosine.
- Nucleotides on strand 1 always pair with specific nucleotides on strand 2.
- Replication: a critical process of the DNA molecule.
- Sometimes chromosome replication errors can have clinical consequences, such as mutations.
Sex Chromosomes and Sex-Linked Traits
- Autosomal chromosomes: typical chromosomes that come in matched pairs.
- Sex chromosomes: the pair of chromosomes that determines an individual's sex.
- Females have XX chromosomes, males have XY chromosomes.
- Sex-linked traits: traits influenced by genes on the sex chromosomes.
- All controlled by genes on the X chromosome.
- Dominant sex-linked traits on the X chromosome will be seen more commonly in females.
- Recessive sex-linked traits on the Y chromosome more commonly in males.
Genetic Code and Gene Expression
- Structural genes: contain information for the synthesis of proteins.
- Proteins: long chains of amino acids.
- Control the physiological activities of cells and are important components of cellular structure.
- Stretches of DNA that lack structural genes include portions called promoters/enhancers.
- Promoters/enhancers: determine whether particular structural genes are converted into proteins through a 2-phase process called gene expression.
- Control of gene expression by promoters is an important process because it heavily influences how a cell will develop and function once it is mature.
- Gene expression involves 2 phases: transcription (DNA base-sequence code to RNA base-sequence code) and translation (RNA base-sequence code to protein).
Transcription
- Strand of DNA unravels and serves as a template for the transcription of a short strand of RNA.
- Ribonucleic acid (RNA): contains the nucleotide base Uracil instead of Thymine and has a phosphate and ribose backbone instead of a deoxyribose backbone.
- Messenger RNA: the strand of transcribed RNA.
- Carries the genetic code out of the nucleus of the cell.
Translation
- Messenger RNA attaches to any one of the many ribosomes present in the cell's cytoplasm.
- Ribosome moves along the strand of messenger RNA, translating the genetic code as it proceeds.
- Codon: 3 consecutive nucleotide bases along the messenger RNA strand.
- Instructs the ribosome to add 1 of the 20 different kinds of amino acids to the protein it's constructing.
- Each kind of amino acid is carried to the ribosome by molecules of transfer RNA.
Human Genome Project
- Purpose: compile a map of the sequence of all 3 billion nucleotide bases that compose human chromosomes.
- 3 major contributions:
- Establishing genomes for many species, including extinct species, leading to insights into evolution.
- Humans have about 21,000 structural genes, similar to mice, but fewer than corn.
- New technology allows for the study of genomes.### Human Proteome and Gene Expression
- Human proteome: a nearly complete map of the entire set of proteins encoded by our genes
- Only about 1% of human DNA constitutes protein-encoding genes
- Many genes have been linked to each disease, but interactions among genes are difficult to sort out
- Even when many genes are linked to a disease, they often account for only a small portion of its heritability (e.g., 18 gene variants linked to adult-onset diabetes, but they account for only 6% of the heritability)
Modern Genetics: Growth of Epigenetics
- Epigenetics (1942): focuses on mechanisms that influence the expression of genes without changing the genes themselves
- 4 factors that led to the rise of epigenetics:
- Human Genome Project generated new research techniques
- Discovery that protein coding genes constitute only about 1% of human DNA (remaining 99% is "junk DNA")
- Most RNA molecules are small (only 1.2% are of the large protein-encoding variety)
- Mechanisms of gene-experience interactions were unknown
- 5 important discoveries in epigenetics:
- Nongene DNA is not "junk DNA" as it controls structural gene expression
- Epigenetic mechanisms can modulate gene expression (e.g., DNA methylation, histone remodeling)
- Worldwide effort to catalogue the epigenome of each cell type
- Epigenetic effects can involve post-transcription alterations to RNA
- Epigenetic mechanisms can be induced by experiences (e.g., neural activity, hormonal state, environmental changes)
Epigenetics of Behavioral Development
- Epigenetic mechanisms can influence gene expression in response to experiences
- Transgenerational epigenetics: examines the transmission of experiences via epigenetic mechanisms across generations
- Epigenetic mechanisms can control gene expression, influencing behavioral development
Classic Research on Behavioral Development
- Selective breeding of maze-bright and maze-dull rats:
- Cooper & Zubek (1958) study: maze-bright and maze-dull rats reared in impoverished or enriched environments
- Results: maze-dull rats made more errors than maze-bright rats only when reared in impoverished environments
- Tryon (1934) research: behavioral traits can be selectively bred
- Bred fittest maze-bright rats and dullest maze-dull rats for 21 generations
- Results: almost no overlap in maze learning performance between the two groups of rats
Phenylketonuria (PKU): A Single-Gene Metabolic Disorder
- PKU: neurological disorder discovered in 1934, caused by a single gene mutation
- Symptoms: intellectual disability, vomiting, seizures, hyperactivity, irritability, and brain damage
- PKU develops only in homozygous individuals (aa) due to a recessive gene
- PKU homozygotes lack phenylalanine hydroxylase, an enzyme required for the conversion of phenylalanine to tyrosine
- Behavioral symptoms result from an interaction between genetic and environmental factors
Genetics of Human Psychological Differences
- Importance of distinguishing between the development of individuals and the development of individual differences
- Heritability estimates: commonly misinterpreted, they describe the proportion of variation in a trait that can be attributed to genetic factors
- Twin studies: used to study the interaction of genes and experience (nature and nurture)
- Two ways to use twin studies:
- Within-pair comparisons: comparing the similarity of twins reared together or apart
- Between-pair comparisons: comparing the similarity of different twin pairs
- Two ways to use twin studies:
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the basics of genetics, including Mendel's work with pea plants, chromosome structure and function, gene expression, and modern advances in genetic processes, including epigenetics.
