Exam 3 Flashcards
When did earth form?
4.6 billion years ago (bya)
When did life first form/evolve?
- Shortly after
- About 3.8 billion years ago
When did life emerge from water?
?½ million years ago?
billion probably?
When did human emerge?
About 2 million years ago (just a handful of years ago)
Common Descent with Modification
- A principle of the theory of evolution
- Species undergo modification through successive generations
- Changes in species can lead to formation of new, separate species
Species
In its simplest sense, they are different kinds of organisms
- Individual of the same species share genetic similarity and can (potentially) interbreed
- there is no good species concept
Population
-All individuals of the same species occupying a specific area over a particular time
All species have…
- Descended from other species
- A common ancestor lies at the base of evolutionary tree
What is the meaning of life?
Fitness (a measure of the number of successful offspring you leave in the next generation)
-Successful reproduction (leaving behind copies of yourself, or more specifically your genes)
Natural Selection
- Darwin
- An agent of evolution (“agent” means “something that causes”)
- Another basic principle in the theory of evolution
- Process through which a trait (or character) that confers reproductive advantage to an individual spreads in a population over successive generations
Biotic Potential
- Most populations are capable of producing more offspring that can be supported by the environment
- Exponential growth
Process of Natural Selection
-More offspring reproduced than can be supported by the environment
- Within populations, there is variation of traits between individuals:
- some of this variation is heritable
- variation in physical, psychological (or physiological), or behavioral traits with a genetic basis that can be passed onto offspring
- Because of their particular traits, some individuals have higher fitness (leave behind more offspring) than other individuals lacking the traits
- Overtime, beneficial traits passed through the population
Natural selection requires what?
- Competition!
- During competition for resources, some individuals will have an advantage because of physical, physiological, or behavioral traits
- Genetic traits that provided an advantage will be spread within a population, but those that do not will be lost from the population
- Selection through this process will change a population’s phenotype over time
- Individuals do not evolve, populations do!
Evolution
-Any genetically-based change of phenotype in a population over successive generations
What is it that evolves?
-Populations!
Example of allele changes in frog populations
- In original environment, it’s one large population, so they could interbreed
- In environment where species are separated, then they eventually can’t interbreed anymore
- In the different areas, fitness was increased for individuals with coloration that better matched each environment.
Importance of evolutionary thinking?
- Species are not fixed entities, but instead are constantly undergoing modification and change
- Organism today descended from other varieties that existed before them
- Humans have descended from other organisms that existed before them
Author and information of author of natural selection book?
- Charles Darwin
- Book is on the origin of species by means of natural selection (1859)
- Developed existing ideas about descent with modification
- Acquired a large body of supporting evidence
- Perceived natural selection as the primary force driving descent with modification
Other guy who isn’t Darwin and info on him?
- Jean-Baptiste de Lamarck (1809, before Darwin)
- Evolution of acquired characters
- Believed over time, an organism could acquire enough changes that one species could diverge into two, but also believed organisms change form over generations through inheritance of acquired characteristics (which is very wrong; examples of gauges, giraffes, etc.)
- REMEMBER: ON TEST, HE WILL HAVE QUESTION LIKE THE ONE ON GIRAFFES, AND THE ANSWER WILL (MOST LIKELY) BE DARWIN’S THEORY
Five Agents of Evolution?
- Natural Selection
- Sexual Selection
- Gene Flow
- Genetic Drift
- Mutation
Where do traits come from?
Mutations!
Mutation (in terms of traits and evolution)
- It’s a change in DNA sequence
- The only means by which new genetic information is generated
- Most are detrimental or harmless, but rare few are beneficial to organisms’ fitness
- Beneficial mutations are the building blocks of evolutionary change
What is the importance of the opsin gene mutation in primates?
- Mutation that duplicated an opsin gene
- Eventually mutated enough to see more color
Gene Flow
- The movement of alleles from one population to another by migration
- Introduce “novel” alleles to a population from some other population
Genetic Drift
-Chance alteration of allele frequencies in a population (change in allele frequencies)
Types:
- Founder Effect
- Population Bottlenecks
- Inbreeding (not focusing on this)
Founder Effect
- Type of genetic drift
- New population is started by a few individuals that are not representative of genetic diversity in the original population
- Colonization of a new habitat by a few individuals that then give rise to a new population
- Founding individuals do not represent the total genetic variation in original population
- Ex: founder effect in red spotted toads
- Rapid range expansion with a series of founder events
- Leading to reduced genetic diversity
Population Bottleneck
- Type of genetic drift
- Follows substantial population decline
- Surviving individuals do not represent genetic diversity of the original population
- Survival during the decline is random
- Chance of surviving is random; not based on selection of any trait or characteristic (if it was, it would be natural selection – not bottleneck)
- Ex: Northern elephant seals
- Original population: had high genetic diversity →
- Hunting in late 1800s: genetically reduced populations →
- Survivors had little genetic diversity →
- The difference is reflected in today’s population
-*Look in Evolution Parts 1 & 2 Packet
Sexual Selection
- Differential reproductive success based on differences in the success of obtaining mates
- Female mate choice
- Nonrandom mating
- Ex. Guppy female picking long tail, heavy spotted males.
- Controlling access to mates
- Ex: great-tailed grackles; local version called boat-tailed grackle
How species come into being?
-Speciation
Allopatric speciation (“of other countries”)
- Occurs when the geographical range of a species is split into discontinuous parts by formation of barriers to gene flow
- Could still mate with them but don’t
- Hypothetical example of forest frogs:
- Populations become isolated in different areas
- If enough gene flow occurs, the population will remain genetically similar
- But if gene flow is lacking, populations diverge
- After time, if individuals from diverging populations can no longer reproduce, speciation has occurred
Reading Evolutionary Trees
- Example in Evolutionary 1 & 2 Packet
- Example using the evolution of terrestrial animals in the phylum: Chordata
- Evolution of terrestrial vertebrates
- Vertical distance represents time
- Ancestral Characters: Existed in the common ancestor
- Derived Characters: unique to taxa (group)
- Remember mammals did/do lay eggs! Platypus
Evolution of the Great Apes
- When we shared a common ancestor:
- About 12 million years ago with orangutan
- About 6 million years ago with gorilla
- About 4.5 million years ago with chimpanzees
- Chimpanzees are more closely related to us than to gorillas
Tissue
A group of cells of a similar type that work together for a common purpose
Four Types of Tissue?
- Epithelial
- Connective
- Muscle
- Nervous
Epithelial Tissue
-Covers body surfaces; lines cavities and organs
- Shapes:
- Squamous
- Cuboidal: can be simple (function = secretion) or stratified (function = protection)
- Columnar: simple (single layer; good for getting things in and out) or stratified
-Look at figure/graph in book
Connective Tissue Types
- Most abundant and has various forms
- Cells embedded in extracellular matrix composed of protein fibers and ground substances
- Extracellular = outside of cell
- Matrix - structure implying that it doesn’t mix, yet it works together
- Protein Fibers = soluble protein fibers
- Collagen - Strong, ropelike, withstands pulling
- Elastic - Contains coils, stretches, then recoils
- Reticular - Thin, networks of collagen
- Ground Substances = cell secretions
- Solid, gelatinous, or fluid
- Various Forms:
- Binds
- Supports
- Transports
- Stores Energy
-Come in 2 types: proper and specialized
Proper Connective Tissue
- Type of connective tissue
- Areolar
- Adipose
- Dense
Areolar
- Type of proper connective tissue
- widely distributed under skin, around organs, and muscles
- structure and cushions
- think about it looking like a net
Adipose
- (fat) found under skin, around organs
- energy storage, insulation, cushioning of organs
Dense
- tendons and ligaments
- function = attachment and movement
Specialized Connective Tissue
- Type of connective tissue
- Cartilage
- Bone
- Blood
Cartilage
- joint cartilage (lines bones)
- absorbs shock (disks between vertebrae)
- more flexible cartilage in ears and nose
Bone
- for structure, protection, and movement
- bones are alive!
- storage of lipids (yellow marrow) and minerals (calcium, phosphorus), and production of red blood cells (red marrow)
Blood (in terms of tissue)
- cells and cell fragments (platelets)
- fibers = soluble proteins (obvious when blood dries and forms clots)
- main function is transport (of oxygen, CO2, nutrients, etc.)
- Plasma = liquid matrix
- Look at table in book
Muscle Tissue
- Skeletal
- Cardiac
- Smooth
Skeletal
- type of muscle tissue
- found around bones
- voluntary contraction
- cylindrical, striated cells with many nuclei
Proteins: Actin & Myosin
-Allows for muscle contraction
Cardiac
- type of muscle tissue
- found only around heart
- wall of heart, pumps
- involuntary contraction
- branching, striated cells with one nucleus
Smooth
- type of muscle tissue
- found around intestines and urinary tubules
- walls of intestines, blood vessels, etc.
- involuntary contraction (constricts)
- nonstriated, one nucleus
Nervous Tissue
-Associated with nervous system – nerves, brain, spinal cord
- Cell Types:
- Neurons
- Neuroglia
Neurons
- They are nerve cells
- Generate and conduct nerve impulses
Neuroglia
-Provides nutrients, insulates, protects neurons
Organ
-Structure composed of two or more DIFFERENT tissues that work together
Integumentary System
- Skin
- includes sweat glands, oil glands, hair, nails
- large organ
For:
-Protection: of physical and chemical factors and pathogens (invasion)
- Limits water loss: keratin (keratinization)
- Makes you waterproof
- Temperature Regulation
- Excretion: of wastes
- Sensory: detection of external stimuli
Skin Layers
- Two layers:
1. Epidermis
2. Dermis
Epidermis
- Layers of epithelial cells
- Constantly shed and replaced
- Keratinized outermost are dead (waterproof)
Dermis
- Lower level of skin
- Dense, connective tissue
- Blood vessels, hair follicles, glands, nerves
Skin Color
- Two factors:
- Pigment:
- melanin – produced by melanocytes
- colors dependent on form of melanin produced: yellow-red or black-brown & size of granules
- Blood Flow:
- amount of oxygen level
- High O2 = ruby red
- Low O2 = deep red-bluish
Accessory Structures
- Hair = modified skin cells
- Nails = modified skin cells
- Glands = oil, wax, sweat
- Functions: insulation, protection, or sensory
Homeostasis of Body Temperature
- Maintenance of favorable (stable) internal conditions in the face of external conditions
- Organ systems interact to provide controlled environments for cellular functions
- Sensor (receptor) –> Control Center –> Effector
- Temperature controlled by hypothalamus – set point is 37 degrees C
- Skin receptors sense surface temperature
- Internal receptors monitor blood temperature
- Brain initiates mechanisms (stimulates effectors) that produce or conserve heat
- When set point is reached, sensors no longer send signals to the hypothalamus, so hypothalamus stop signalling effectors
- Thus, a negative feedback (just like thermostat at home)
Skeletal System
- Support
- Movement
- Protection
- Storage (of fat and minerals)
- Blood cell production
Compact Bones
- Dense
- Central cavity (in long bones)
- Contained in blood vessels, yellow marrow
- Covered by membrane: periosteum
- Contains blood vessels, nerves
-Yellow marrow
Spongy Bone
- Lattice-like structure: latticework of tiny beams
- Contains red marrow
Bone
-Hard and resilient
- Made up of matrix
- Bone is a connective tissue
- mineral salts: hardness from mineral salts
- calcium and phosphorus
-Elastic protein: resiliency from elastic protein collagen
Bone Structure
-Covered by membrane, periosteum
-Blood vessels, nerves
Associated with bone growth and repair
- Bone cells = osteocytes
- Bone is made of repeating units - Osteons which consists of bone cell called osteocytes
Osteoblasts
- Osteo = bone
- Blast = beginning bud
- Make bone
- Cells that create matrix by secrete proteins and minerals (know dominant minerals, like calcium)
- Related to osteocytes
- During development bones start as cartilage, over time osteoblasts convert this bone
- Some osteoblasts form a matrix around themselves and become osteocytes
Bone Remodeling
- Lifelong process of deposition and breakdown
- Renews bone, regulates blood, calcium, and other minerals
- Osteoclasts
- Osteoblasts
- Calcitonin
- Parathyroid hormone stimulates osteoclasts
Osteoclasts
- Cells that breakdown bone
- Releasing calcium and other minerals
Osteoblasts
- Secrete new bone matrix
- Removes calcium and other minerals
- Hormone regulation (from thyroid):
- Calcitonin stimulates osteoblasts and inhibits osteoclasts
- Parathyroid hormone (PTH) stimulates osteoclasts
Calcitonin
-Stimulates osteoblasts and inhibits osteoclasts
Osteoporosis
-Disorder that results in weak, brittle bones
- Bone remodeling problem
- Estrogen aids in remodeling process
- Calcium is needed
- Vitamin D is needed for calcium absorption
Bone Repair
- Occurs when bone breaks
- Bleeding: clotting – bleeding from blood vessels in bone and periosteum
- Fibroblasts: formation of callus – connective tissue cells ingrown inward from periosteum, forming a callus (mass)
- Secretion of cartilage: these cells transform and begin secreting cartilage
- Transformation of cartilage to bone: osteoblasts (from periosteum)
Axial and Appendicular Skeleton
- Axial = Head, neck, body
- Appendicular = Arms, legs
- Skull is NOT one bone
- 14 facial bones
- Rib cage: protect internal organs
- Sternum (breastbone)
- 24 (12 pairs) of ribs
- Vertebral Column
- Vertebrae - 26
- Pelvic Girdle
- 6 fused bones
- Protects internal pelvic organs
- Supports weight of vertebral column
Joints
-Bendable places where bones meet
- 3 Types:
- Fibrous Joints
- Cartilaginous Joints
- Synovial Joints
- Cartilage layers that allow sliding of bone
- Membranes and cells that secrete fluid
Fibrous Joints
- Immovable
- Ex: Bones in skull
Cartilaginous Joints
-Immovable to slightly movable
- Ex: In rib cage (it can expand and stuff)
- Vertebral column
Synovial Joints
- Freely moveable
- Ex: Knee
- Cartilage layers that allow sliding of bone
- Membranes and cells that secrete fluid
How many freely moveable joints to humans have?
-More than 30
Muscular System
- Humans have more than 600 muscles
- Excitable (respond to stimuli)
- Contractile
- Extensible (stretch)
- Elastic (return to original length/form)
Structure/General Characteristics of Muscles
- Bundles: bundles of bundles of bundles of bundles
- Inside bundles are muscle fibers = muscle cells
- Muscle cell consist of many myofibrils
- Striated - Alternating (light & dark) bands of actin and myosin filaments
- One muscle cell extends from stationary attachment to a movable attachment
- Muscles come in antagonistic pairs
- One muscle opposes the other
- Ex. Tricep and Bicep
Sarcomeres
- They are functional units of contraction
- Each muscle cell contains thousands of sarcomeres
- Made up of protein myofilaments: actin and myosin
Movement of Sarcomeres
- (Sliding filament model)
- Sliding of actin filaments across myosin filaments
- Requires ATP: restoring myosin filaments has ADP and P bound to its head
- Uses energy to get immediate energy
-Thousands of sarcomeres sliding = contraction
Motor Unit
- Nerve (motor neuron) and the muscle cells it stimulates to contract
- Strength of a muscle contraction involves recruitment of more and more motor units
- Motor neuron may affect only a few muscle cells or thousands
- Think of lifting chair vs. lifting soda can example
Why do we prep energy for muscles?
To save time/prepare for use in an instance
Difference between lifting a can of soda vs. chair?
Number of motor units needed to initiate it (contraction movement)