Exam 4

Question 1

• Discuss different types of cell division: binary fission, mitosis and meiosis. Apply this knowledge to examples.

Answer 1

o Binary fission – the process when bacteria reproduce asexually into 2 cells
o Mitosis – process in making more of the diploid cells, somatic cells for growth and repair, makes a single cell divide into two identical daughter cells (cell division)
o Meiosis – process of making haploid gametes, eggs and sperm, reduces the number of chromosomes in the parent cell by half and produces four gamete cells.

Question 2

• Understand and explain somatic cells, gametes, karyotype, autosomes, sex chromosomes, haploid and diploid

Answer 2

o Somatic cells – are any cell of the body except sperm and egg cells, are diploid containing two sets of chromosomes from each parent
o Gametes – organism’s reproductive cells, are haloid cells and carries one copy of each chromosome.
o Karyotype – prepare from mitotic cells that have been arrested in the metaphase or prometaphase portion of the cell, chromosomes assume their most condensed conformations.
o Autosomes – any of the numbered chromosomes as opposed to the sex chromosomes, controls the inheritance of all organism’s characteristics.
o Sex chromosomes – type of chromosome that participates in sex determination, X and Y
o Haploid – produce by men for sperm and women for ova
o Diploid – when ova and sperm combine in fertilization then it makes a diploid zygote that grows into an embryo.

Question 3

• Describe and compare asexual and sexual reproduction. Apply this knowledge to examples.

Answer 3

o Sexual production mixes up the genes, in crossing over in prophase 1 of meiosis 1, random alignment, and independent assortment of chromosomes in metaphase 1 of meiosis 1, random combination of gametes at fertilization.
o Asexual reproduction involves one parent and produces offspring that is genetically identical to the parent
o Sexual production involves two parents and produces offspring that are genetically unique.

Question 4

• Be able to compare mitosis and meiosis and the results of the types of division.

Answer 4

o Mitosis – a asexual reproduction that makes more diploid cells
 Somatic cells for growth and repair
o Meiosis – sexual reproduction that require sperm and ova

Question 5

• Explain mitotic check points and their significance.

Answer 5

o Mitotic checkpoint is a signaling cascade that arrests the cell cycle in mitosis when even a single chromosome is not properly attached to the mitotic spindle.
o G1/s checkpoint, intra-S checkpoint, and G2/M checkpoint

Question 6

• Discuss the advantages of sexual reproduction.

Answer 6

o Produces genetic variation in offspring
o Species can adapt to new environments due to variation, survival advantage
o Disease is less likely to affect all the individuals in a population

Question 7

• Be able to explain the mechanisms of meiosis that leads to unique offspring.

Answer 7

o Meiosis is a reciprocal process to the joining of two genomes that occurs at fertilization.
o Organisms generate new cells is through cell division, parent will divide and produce identical daughter cells.

Question 8

• Describe the sources of genetic variation in a population, including the differences in the kinds of variations produced by mutations and by recombination. Apply this knowledge to examples.

Answer 8

o 2 processes
 Change in DNA called mutations
• Original source of genetic variation
 Recombination (gene shuffling)
• DNA are broken and different combinations of alleles created the way to produce new combinations of alleles
 Immigration of genes
• New organisms join a population, taking with them their genes.

Question 9

• Define mutation.

Answer 9

o DNA gene is damaged or changed in alter genetic message carried by that gene.

Question 10

• Describe how natural selection and mutations interact to result in evolution. Apply this knowledge to examples.

Answer 10

o Mutations – random and accidental & permanent changes in DNA
 Mutations - Random and accidental & permanent changes in DNA
• Point Mutations - One base is changed
• Insertion Mutations - DNA segments is inserted into the middle of existing sequence
• Deletion mutations - DNA segment is deleted
• Duplication mutations - DNA segment is copied into 2 of the same gene
o Entire genome might be duplicated
• Inversion mutation
o Inverted - DNA segment is flipped around and inserted backwards
• Fused chromosomes - chromosomes are fused together
o changes the # of chromosomes
• Horizontal gene transfer - genes passed from 1 organism to another
o passed between species
o occurs today in bacteria
 Genetic Drift - changes in gene pool populations by a random chance
 Gene Flow - movement of alleles between populations
• immigration - alleles move into a population
• Emigration - alleles move out of population
 Natural selection - environment selects the traits
• pressure for traits (phenotypes) increase chances of survival and reproduction in that environment
• only occurs when individuals in a population differs in reproductive success.
• Sexual Selection

Question 11

• Explain the differences between harmful, neutral, and beneficial mutations and their effects on organisms’ fitness.

Answer 11

o Harmful – causes genetic disorders or cancer
o Neutral – changes in DNA sequence that are neither beneficial nor detrimental
o Beneficial – more common through natural selection, allows organisms to be more likely to survive for fitness

Question 12

• Describe different types of mutations: point mutation, insertion mutations, deletion mutations, duplication mutations, inversion mutations, fused chromosomes, and horizontal gene transfer. Apply this knowledge to examples.

Answer 12

o Point Mutations - One base is changed
o Insertion Mutations - DNA segments is inserted into the middle of existing sequence
o Deletion mutations - DNA segment is deleted
o Duplication mutations - DNA segment is copied into 2 of the same gene
 Entire genome might be duplicated
o Inversion mutation
 Inverted - DNA segment is flipped around and inserted backwards
o Fused chromosomes - chromosomes are fused together
 changes the # of chromosomes
o Horizontal gene transfer - genes passed from 1 organism to another
 passed between species
 occurs today in bacteria

Question 13

• Explain what is meant by evolutionary fitness and give examples.

Answer 13

o How well a species is able to reproduce in its environment. If they’re no longer reproducing then they are no longer evolutionarily fit.

Question 14

• Explain the evolutionary mechanisms of genetic drift, gene flow, and sexual selection. Give examples.

Answer 14

o Genetic drift – can change in gene pool populations by random chance
o Gene flow – movement of alleles between populations
 Immigration – alles move into a population
 Emigration – alleles move out of population
o Sexual selection – members of one biological sex choose mates of the other sex to mate with

Question 15

• Describe and give examples of negative selection, positive selection, stabilizing selection, and balancing selection.

Answer 15

o Negative selection – selective removal of alleles that are deleterious.
 Ex. Species stays the same
o Positive selection – increase in prevalence in a population
 Ex. ability to digest lactose
o Stabilizing selection – type of natural selection that favors the average individuals in a population
 Ex. Stabilizing human birth weight, # of offspring, & camouflage
o Balancing selection – when multiple alleles are maintained in a population
 Ex. Sickle cell disease, S for sickle cell hemoglobin and A for normal hemoglobin

Question 16

• Describe how natural selection and mutations interact to result in evolution. Apply this knowledge to examples.

Answer 16

o As mutations occur natural section decides which mutations will live on and which ones will die out. If mutation is harmful, the mutated organism has much decreased chance of surviving and reproducing.

Question 17

• Discuss misconceptions about evolution.

Answer 17

o Populations evolves, not the individuals
o Natural selection involves organisms trying to adapt
o Natural selection give organisms what they need.
o Humans can’t negative impact ecosystems
o Natural selection acts for the good of the species
o All traits of organisms are adaptations

Question 18

• Describe variations in populations and factors that contribute to the variations.

Answer 18

o mutations are random but permanent to the DNA
o 2 factors for mutations
 Errors in copying during reproduction
• mistakes happen often
 direct damage caused by exposure of cells to radiation or chemicals
 mutations can be harmful, helpful, or neutral
• harmful mutations causes populations to decrease
• helpful mutations increase the fitness to the individual for the population
• neutral mutations has no fitness.
 lethal mutations - mutations rise to structural, functional, or behavioral alterations
 mutations have a cumulative effect of millions of years of biodiversity

Question 19

• Define polymorphisms, gene pools, genetic equilibrium, microevolution and macroevolution.

Answer 19

o Polymorphisms – human blood type is different or skin
o Gene pool – alleles that make up the genes of a population
o Genetic equilibrium – theoretical
 Change in allele where
• Mutations never occur
• population is infinitely large
• population is isolated from other populations of the species
• mating is random
• all individuals survive to produce the same number of offspring
 All 5 of these conditions are never met in nature
 Natural populations are never in equilibrium
 Microevolution is always occurring in natural populations because the processes the drive it are always operating
o Microevolution – evolution within a population or species, always occurring in natural populations because processes the drive that are always operating
o macroevolution - change in allele frequencies within a single species or population
 evolutionary patterns on a larger scale
 occurring over millions of years.
 preadptation or exaptation
 traits serve a very different purpose in modern species
 exapations - flight feathers in modern birds are an exaptation of insulating feathers in dinosaurs
 stasis - simple evolutionary patterns
• evolutionary pattern in which linage persists with little or no change over time.

Question 20

• Discuss the mechanism of evolution.

Answer 20

o Mutations – occurs whenever a mistake in the DNA occurs in the heritable cells of an organism
o Genetic Drift – random fluctuations in frequencies of alleles from generation to generation due to chance events.
 Genetic drift can cause triats to be dominant or disappear from a population
o Gene flow – result of genes being transferred from one population to another
 Migration, immigration
o natural selection (sexual selection) – intrasexual selection or competition between members of the same sex and members of one sex choose members of the opposite sex.

Question 21

• Know the processes of microevolution: mutations, natural selection, genetic drift, gene flow.

Answer 21

o Microevolution mutations – change in allele frequencies that occur over time within a population
o Natural selection – how many offspring organisms of a particular genotype or phenotype leave in the next generation

Question 22

• Discuss reproductive isolation: prezygotic and post-zygotic.

Answer 22

o Reproductive isolation - The inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences.
o Prezygotic – prevents the fertilization of eggs
o Post-zygotic – prevents the formation of fertile offspring

Question 23

• Describe coevolution and adaptive radiation.

Answer 23

o Coevolution – reciprocal evolution change in 2 interacting species
 2 species that have close ecological interactions evolve together that over time they require each other to survive
o Adaptive radiation – evolution of ecological and phenotypic diversity within a rapidly multiplying linage.

Question 24

• Explain evolutionary fitness.

Answer 24

o Organism’s success in reproduction

 Highest amount of offspring

Question 25

• Define selection pressure and the types of selection pressures.

Answer 25

Selection Pressures - external agents which affect organism’s ability to survive in a environment
• can be negative (decreases the occurrence of trait) or positive (increase proportion of a trait)
• negative selection - selection against a particular trait (recessive)
• positive selection - selection for a particular trait (dominant)
• sexual selection - natural selection, one sex mates with other sex
• stabilizing selection - selection against the extreme of a trait > more organisms with traits
o selection for intermediate traits (baby weight is against small and large)
• balancing selection - occurs in sexual organisms with 2 sets of alleles (heterozygous)
o heterozygous individuals are better adapted to the environment than homozygous individuals
o S - allele code for sickle cell
o A - allele code for normal hemoglobin

Question 26

• Know the difference between heterozygous and homozygous alleles.

Answer 26

o Homozygous copies two of the same allele, dominant alleles

o Heterozygous one of each type of allele, one dominant and one recessive

Question 27

• Describe adaptation and explain the role of natural selection in their evolution.

Answer 27

Adaptation process: change that occurs in a population over time as natural selection influences which organisms survive and reproduce in a particular environment. Adaptation result: the traits that confer reproductive success.
Adaptation is any traits that allows an organism to be successful (to survive and reproduce) in a given environment
Ex. Thick fur, good eyesight
Inherited from parents not acquired after birth
Different adaptations may be expressed at different times.
Physical, Physiological, behavioral, and any other genetic control provides traits for an advantage
Behavioral Traits:
• hunting techniques (for predators)
o evasion techniques (for prey)
Physiological traits - ability to break down lactose

Question 28

• Recognize a variety of adaptations and discuss how natural selection could have resulted in the evolution of these features.

Answer 28

When natural selection acts on a traits that is correlated with increased reproductive success, then natural selection causes adaptive evolution
Halophytes - plants that live in salty conditions
• conserve water, and excrete excess salt on leaves.
• are able to survive when their roots are covered with water
All traits arose as mutations and were selected for by natural selection
A successful adaptation in one environment may not be favored in a different environment
Think blubber on walrus
• adaptation in cold arctic
• handicap in warming oceans

Question 29

• Describe the evolution of a complex adaptation that requires many different parts working together. Explain the roles of gene duplication and gene recruitment in the evolution of these adaptations.

Answer 29

o gene recruitment and gene duplication are important for the evolution of new adaptations
 gene recruitment is an evolutionary transition in which a gene begins to be expressed in another organ, or in other context
o gene duplication is a mutation that produces an extra copy of a gene
o a new adaptaions occur when existing adaptation, that might have completely different function, is modified
o Egg and sperm fuse to produce a zygote that develops into a embryo then the cells begin to differentiate
 Bone, Neurons, cardiac tissue, epithelium
o all cells are using the same set of genes
o source of the differences of these cells is a protein known as a transcription factor
 transcription factor is a protein that bind to specific DNA sequences
o some transcription factors can turn genes on
 others turn genes off
o embryo develops cells use transcription factors to turn gene on and off in a particular way
o Genes for transcription factors can mutate
o these mutations can provide an opportunity for patterns of new development
o transcription factors are essential for making right proteins in the right places
o Networks of genes control the development of animal embryos
o Hox genes help determine what different segments in a fly embryo will become in the adult

Question 30

• Describe the importance of the “genetic toolkit” (Hox genes) in the evolution of animals.

Answer 30

o Building of the basic body plan. Help lay out the basic body forms of many animals

Question 31

• Explain the factors that constrain evolution.

Answer 31

o Evolutionary constraints are restrictions, limitations, or biases on the course or outcome of adaptive evolution.

Question 32

• Define convergent evolution and apply this concept to examples.

Answer 32

o Convergent evolution – process whereby distantly related organisms independently evolve similar traits to adapt to similar necessities.

Question 33

• Define and apply the terms of gene duplication and gene recruitment.

Answer 33

Gene duplication - mutation produces an extra copy of a gene
Modifies gene for one function - gene for different function
Gene duplication:
• Regulatory regions control when and where the protein is made | Protein-coding DNA
• Duplication into two identical regions
• a regulatory region in one copy mutates and ceases to function as it did before the duplication
• One gene evolves new regulation and function | one gene mutates into a pseudogene with no function | each gene evolves to specialize in one of the functions of the original gene
Gene Recruitment:
• Evolutionary modification of existing adaptation
• A gene is expressed in a different organ or pathway or in some new context.

Question 34

• Know how transcription factors work.

Answer 34

Transcription Factors
• Proteins that bind to regulatory regions associated with specific genes
• Act together to control gene expression
• Some turn genes on
• Some turn genes off

Question 35

• Describe a genetic tool kit and the Hox gene.

Answer 35

o Genetic tool kit – orchestrate the building of the basic body plan
o Hox genes - Involves a group of transcription factors that work together to produce an animal’s body plan
o Previously discussed simple transcription factors that controlled individual proteins
o Groups of transcription factors (TFs) interact
 Transcription factors are proteins > production is controlled by different TFs > cascade
 TFs are all coded for by genes
 Network of genes controls animal development
 An animal’s body shape and structures are controlled by networks of genes
 Get turned on in different sequences and patterns
o Animals use the same genetic tool kit of Hox genes to control the development of their embryos
o controls where body parts develop in an embryo

Question 36

• Detail how the Hox gene control body plans.

Answer 36

o The cluster of genes is responsible for determining the general body plan.
 Decides on the number of body segments of an animal

Question 37

• Be able to discuss how the BMP4 and the Calmodulin (CaM) genes work.

Answer 37

o BMP4 – Bone morphogenetic protein 4, protein coding gene
 Stimulates differentiation of overlying ectodermal tissue simulating bone formation in adult animals
o Calmodulin (CaM) – multifunctional intermediate calcium-binding messenger protein expressed in eukaryotic cells
 Excitation contraction coupling and the initiation of cross-bridge cycling in smooth muscle, responsible for smooth muscle contraction