Test 3 Flashcards
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 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
- 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
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
- Ground Substances = cell secretions
- 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
Muscle Tissue
- Skeletal
- Cardiac
- Smooth
Skeletal
- type of muscle tissue
- found around bones
- cylindrical, striated cells with many nuclei
- voluntary contraction
Cardiac
- type of muscle tissue
- found only around heart
- branching, striated cells with one nucleus
- wall of heart, pumps
- involuntary contraction
Smooth
- type of muscle tissue
- found around intestines and urinary tubules
- nonstriated, one nucleus
- walls of intestines, blood vessels, etc.
- involuntary contraction (constricts)
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 tissues that work together
Integumentary System
- Skin
- includes sweat glands, oil glands, hair, nails
- large organ
For:
-Protection: of physical and chemical factors; of organisms (invasion)
- Limits water loss: keratin (keratinization) - 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
- 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
Sensor - Control Center - Effector
- When set point is reached, sensors no longer send signals to the brain, so…?
- Thus, a negative feedback (just like thermostat at home)
- *This is when external environment is cold
- LOOK IN TISSUES AND ORGANS PACKET FOR CIRCULAR THING
- These either belong here or under “Homeostasis of Body Temperature”
- Skin receptors sense surface temperature
- Internal receptors monitor blood temperature?
- Brain initiates mechanisms (stimulates effectors) that produce or conserve heat
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/Bone Structure
Bone:
-Hard and resilient
- Made up of
- matrix
- mineral salts: hardness from mineral salts
- calcium and phosphorus
-Elastic protein: resiliency from elastic protein collagen
Bone Structure:
- Covered by membrane, periosteum
- Blood vessels
-Bone cells = osteocytes
Osteoblasts
- 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
- Relaxing calcium and other minerals
Osteoblasts
- Secrete new bone matrix
- Removes calcium and other minerals
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
- Skull is NOT one bone
- Like 14 facial bones
- Rib cage: protect internal organs; sternum (breastbone)
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: skull
Cartilaginous Joints
- Immovable to slightly movable
- Ex: In rib cage (it can expand and stuff)
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?
- A helluva lot
- More than 30
Muscular System
- Humans have more than 600 muscles
- Excitable (respond to stimuli)
- Contractile
- Extensible (stretch)
- Elastic (return to original length/form)
General Characteristics of Muscles
- Striated: alternating (light and dark) bands of actin and myosin filaments (proteins)
- One muscle cell extends from stationary attachment to a moveable attachment
- Most are arranged in antagonistic pairs
Structure of Muscles
- Bundles: bundles of bundles of bundles of bundles
- Inside bundles are muscle fibers = muscle cells
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.
Difference between lifting a can of soda vs. chair?
Number of motor units needed to initiate it (contraction movement)
Skeletal Muscle Contraction
- Signal from nerve
- Calcium is needed for muscle contraction
- Power stroke (ADP & P) move off)
- Myosin reactivation uses ATP (energy)
Signaling (of muscle contraction)
- Step 1: Nerve impulse reaches the neuromuscular junction
- Step 2: Acetylcholine released into the junction
- Step 3: Acetylcholine binds to receptors on the plasma membrane of sarcomere, and electrochemical message is generated
- Step 4: Calcium ions released from the sarcoplasmic reticulum – contraction initiated
- LOOK AT BACK OF SKELETAL AND MUSCULAR SYSTEMS PACKET
Neuromuscular junction
Junction between nerve and muscles
Slow-Twitch Muscle Cells
- Contract slowly
- Richly supplied with oxygen (aerobic)
- Abundant mtDNA
- Deliver prolonged, strong contractions
Fast-Twitch Muscle Cells
- Contract rapidly
- Powerful, packed with more actin and myosin
- Less endurance (anaerobic)
Muscular Energy in Muscle Cells
-Energy sources for muscle cells contractions
- Stored ATP:
- about 6 seconds - Stored creatine phosphate:
- molecule used to quickly recharge ATP:
- about 10 seconds - Anaerobic respiration:
- About 30-40 seconds
- For short efforts, this pathway generates ATP from glucose stored in muscle cells faster than…?
- Aerobic Respiration:
- Lower levels of ATP production for long periods
Nervous System
- Central: brain and spinal cord
- Peripheral: nervous tissue outside CNS
What is the basic unit of the nervous system?
- Neuron!
- nerve cell
Neuron (2?)
- Nerve cell
- Excitable cell: generate and transmit information
Three types of neurons?
- Sensory Neurons
- Motor Neurons
- Interneurons
Sensory Neurons
-Conduct signal towards CNS (to brain or spinal cord)
Motor Neurons
-Carry signals from CNS to an effector (muscle or gland)
Interneurons
- Found only in brain and spinal cord
- Interpret sensory signals, initiate response
Reflex Arc
-LOOK IN NEURONS PACKET
- Finger over flame thing
- It would be one motor unit