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Biol1003 Study Notes: Cells, DNA, Skeletal System, Study notes of Biology

Virginia State University (VSU)Biology

These study notes provide a comprehensive overview of key concepts in biology, including the structure and function of the microscope, cell structure, dna replication, the cell cycle, the skeletal system, and joints. The notes are well-organized and include detailed explanations, diagrams, and examples. They are suitable for students taking introductory biology courses.

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Biol1003 Learning Study Notes

The Microscope

•operate the compound light microscope and the dissecting microscope to examine specimens;

1. check the lenses are clean and undamaged

2. swing low power objective

3. switch on the light switch (I = on, 0 = off)

4. adjust light intensity ( on the right hand side of the base) 4-5 is adequate for most specimens

5. position slide on stage

6. focus specimen using the coarse

focusing knob

7. raise condenser and open iris

diaphragm, move specimen aside

8. lower condenser until paper on

light source is in focus

9. adjust iris diaphragm by removing

eyepiece and closing the diaphragm

until

¾ of the field is illuminated

10. replace specimen, and fine focus

11. centre specimen

12. position high power objective

13. adjust iris diaphragm

14. fine focus

•apply a scale to your drawings;

•estimate the size of microscopic

objects; Done in class! 

Discover Study notes of Biology Virginia State University (VSU)

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Biol1003 Learning Study Notes

The Microscope

operate the compound light microscope and the dissecting microscope to examine specimens;
1. check the lenses are clean and undamaged
2. swing low power objective
3. switch on the light switch (I = on, 0 = off)
4. adjust light intensity ( on the right hand side of the base) 4-5 is adequate for most specimens
5. position slide on stage
6. focus specimen using the coarse focusing knob
7. raise condenser and open iris diaphragm, move specimen aside
8. lower condenser until paper on light source is in focus
9. adjust iris diaphragm by removing eyepiece and closing the diaphragm until ¾ of the field is illuminated
10. replace specimen, and fine focus
11. centre specimen
12. position high power objective
13. adjust iris diaphragm
14. fine focus
apply a scale to your drawings;
estimate the size of microscopic objects; Done in class! 

Cell Structure

describe the structures and functions of a cell;
Cell membrane
- Plasma membrane
- Phospholipid bilayer
- Centre is hydrophobic / outside is hydrophilic
- Protein channels
  1. Passive = relies on concentration or ionic gradient
  2. Active = requires energy in the form of ATP
Nucleolus
- Housed within nucleus
- Assemble ribosomes
Nucleus
- Houses DNA
- Controls cellular processes
Ribosomes
- Involved in translation
- Consists of 2 subunits (small and large)
- Not membrane bound
Rough ER
- Has ribosomes
- Involved in protein synthesis
Smooth ER
- Involved in lipid assembly and detoxification
- Stores and releases Ca (sarcoplasmic reticulum)
- No ribosomes
- Concentrated in liver
Golgi
- Processes and packages proteins such as carbs or lipids
- Hormone and channel proteins
Lysosomes
- Cell defence
- Digest particles by secreting digestive enzymes
- Created by golgi
Cytoskeleton
1. Microtubules
  - Centrioles
  - Flagella and cilia
  - Composed of protein subunits 5nm in diameter
  - Whole tubule 25nm in diameter
2. Intermediate filaments
  - Mechanical support
  - Actin and myosin
  - Diameter 10nm
3. Microfilaments
  - Microvilli

Mitochondria
- Has own DNA (suggests it was originally a single organism)
- Site of cellular respiration
- Theory that it was originally a bacteria which was engulfed
explain surface area to volume ratios in relation to cells;
The rate of diffusion into or out of a cell decreases as the cell increases in size because there is less surface area per unit of volume across which to exchange substances
The maximum size to which a cell can grow is determined by the rate of diffusion of nutrients and gases across the cell surface
A cell can increase the maximum size to which it can grow by developing an intracellular transport system (membrane systems, e.g. ER), compartmentalise processes (organelles)
Heat loss per unit surface area is equal in the two animals, but the smaller animal will lose heat at a faster rate relative to its volume because the surface area to volume ratio (SA:V) is increasing with decreasing size.
Larger cells have a lower SA:V ratio so their overall heat loss relative to surface area will be lower than that of smaller cells
The principle also applies to substances that are transported in an organism, or across a cell membrane (e.g. water, oxygen, wastes). Small cells have a large SA:V ratio compared to large cells. As cell size increases, the rate of movement of substances across the surface becomes insufficient to serve all the volume of the cell
describe the structure of DNA and how it replicates;
DNA
- The components of a nucleotide are a sugar, a phosphate base and a nitrogen base.
- DNA is often described as a ladder.
- components that make up the "sides ('backbone') of the ladder" are the phosphate and sugar groups
- "rungs of the ladder" are the nitrogen bases.
- complementary base pairs are adenine and thymine, and cytosine and guanin
Replication
- The two DNA strands are separated and the replication machinery is assembled at the replication fork
- The two DNA strands are used as template strands to create newly synthesised DNA strands
- The key feature that allows DNA to produce two molecules with the same DNA sequence is due to Chargaff’s rules
- This means adenine in one strand only hydrogen bonds with thymine, and guanine only bonds with cytosine
- By this mechanism one double stranded DNA molecule gives rise to two new identical molecules
- Each copy contains one newly synthesised strands and one original strand
- Semi conservative process as one half of the molecule is conserved from the original molecule

Replication begins at the origin of replication (sequence of nucleotides)
Helicase unwinds the double stranded DNA helix and single stranded binding proteins react with the single stranded regions to stabilise it
DNA pol III is the major enzyme involved in DNA rep
DNA pol III can only add a nucleotide to the 3’ and cannot initiate a nucleotide chain
RNA pol called a primase constructs an RNA primer of about 10 nucleotides complementary to the parent DNA
DNA pol III can then add deoxyribonucleotides to synthesise the new complementary strand of DNA
The leading strand elongates towards the replication fork by adding nucleotides to the growing 3’ end
The lagging strand which elongates away from the replication fork is synthesised discontinuously with okazaki fragments
DNA pol III reaches RNA primer on the lagging strand it is replaced by DNA pol I which removes the RNA and replaces it with DNA
DNA ligase then attaches and forms phosphodiester bonds
DNA is further unwound, new primers are made, and DNA pol III jumps ahead to begin synthesising

another okazaki fragment

Lacunae – houses osteocyte

Cannaliculi – branching tubular passages radiating like wheel spokes from each bone lacuna to connect with the canaliculi of adjacent lacunae, and with the haversian canal.

Lamellae – concentric and interstitial
Volkmanns canals – where vascular supplies are (blood vessels)
explain how bone is formed;
Bone formation
- Known as ossification
- Modelled by connective tissues
  1. Intramembranous – membrane forms around the brain and forms a template for the bones to grow and form the skull
  2. Endochondriol – cartilage is used as a template instead of a membrane (used for most bones)
Occurs in the first 3 months of an embryo

At 6 weeks a cartilaginous model is formed
Periosteum begins to develop
Compact bone develops, blood vessels infiltrate to supply nutrients, primary ossification centre formed
Medullary cavity formed, secondary ossification centres formed
Compact bone and growth plate

Bone remodelling – bone is added by osteoclasts at epiphyseal lines unitl 18y.o. (females and 20y.o. (males)
identify the bones of the axial and appendicular skeletons and state their functions;
Axial skeleton
- Skull – frontal, periatal, temporal, occipital
- Vertebrae – cervical, thoracic, lumbar, sacrum, coccyx
- Ribs
- Sternum
Appendicular skeleton
- Pectoral girdle
- Pelvic girdle
- Upper and lower limbs

Cervical

Axial

Sternum
- Manubrosternal Joint. Between the manubrium and the body of the sternum, fibrocartilagenous, forms the manubrosternal angle through which passes the manubrosternal plane.
- Xiphisternal Joint. Between the body of the sternum and the xiphisternum, fibrocartilagenous, xiphisternal plane.
Ribs
- Costocorporal. R1-12, head of rib with vertebral body (bodies), synovial.
- Costotransverse. R1-10, articular tubercle of rib with transverse process of vertebra, synovial.
- Costochondral. R1-10, chondral end of rib with costal cartilage, cartilagenous.
- Sternocostal. R1-7, costal cartilage directly with sternum, true ribs, synovial except for R1 which is fibrous.
- Interchondral.R8, 9, 10 costal cartilage with the costal cartilage of R 7, false ribs, synovial.
Vertebrae
- Intervertebral Disc Joints. Between the bodies of the vertebrae, symphysis.
- Zygopophyseal Joints. Between the articular processes, synovial, sliding, anterior-posterior orientation allows mainly rotation in the thoracic region Appendicular
Scapula on Chest Wall
- Not a joint but acts like one
- six major directions of movement
Shoulder Joint (SJ)
- Formed from the humerus and scapula
- a synovial ball and socket joint
- six major directions of movement, flexion, extension, abduction, adduction, medial and lateral rotation.
Elbow Joint (EJ)
- Formed from the humerus, radius and ulna
- a synovial hinge joint
- two major directions of movement, flexion, extension.
Radio-Ulna Joints (SRUJ, IRUJ)
- Formed from the radius and ulna
- a set of synovial pivot joints
- two major directions of rotatory movement called pronation and supination.
Wrist Joint (WJ)
- Formed from the radius and the proximal row of carpal bones
- a synovial ellipsoid joint
- four major directions of movement, flexion, extension, abduction, adduction.
Intercarpal Joints (ICJ)
- Many joints between the carpal bones
- synovial with little movement.
Carpo-Metacarpal Joints ( CMJ’s x5)
- Five synovial joints
- first CMJ 1 formed from trapezium and the base of the first metacarpal bone, a saddle joint with five directions of movement, flexion, extension, abduction, adduction, opposition, contributes significantly to thumb mobility
- the four medial CMJ’s are relatively immobile.
Metacarpo-Phalangeal Joints (MPJ x5)
- Between the heads of the metacarpals and the proximal phalanges

four major directions of movement, flexion, extension, abduction, adduction, except the thumb which has only two, flexion, extension.
Interphalangeal Joints (IPJ x9)
Formed between the phalanges
synovial hinge joints with two directions of movement producing digit flexion and extension
Sacroiliac Joint (SIJ)
Between the hip bone and the sacrum
partly synovial partly fibrous
little movement.
Hip Joint (HJ)
Between the hip bone and femur
a synovial ball and socket joint
six major directions of movement, flexion, extension, abduction, adduction, medial and lateral rotation
Knee Joint (KJ)
Between the femur, patella and tibia
a composite synovial hinge joint with some modification
two major directions of movement, flexion, extension.
Tibio-Fibula Joints (STFJ, ITFJ)
Between the tibia and fibula
superior one is synovial inferior fibrous
relatively immobile
Compare these joints with the RUJ’s.
Ankle Joint (AJ)
Between the tibia, fibula and the talus
a synovial hinge joint
two major directions of movement
Moving the foot up is dorsiflexion moving the foot down is plantar flexion
Joints of the Foot
Many
Provide some resilience (energy absorption), flexibility and moulding
Allows inversion and eversion of the foot and flexion and extension of the toes
explain how muscle action causes movement at joints and define an antagonistic muscle pair;
agonist = contraction of this muscle decreases the angle of the joint
antagonist = contraction of this muscle increases the angle of the joint
contraction of muscles is how movement is created as the muscles are attached to the bones
contraction pulls on the bones but never pushes
define a motor unit in a muscle and describe the structure of a muscle fibre;
A motor unit is made up of a motor neuron and the skeletal muscle fibres innervated by that axon

Downloaded by studjj murrry ([email protected])

Skeletal muscle

Pulls on bones to move them
Striated
Under voluntary control
describe peristaltic muscular activity of the alimentary canal, the urinary tract and the reproductive tract
Peristalsis is the wave of circular smooth muscle relaxation/ contraction followed by the wave of circular smooth muscle contraction/ relaxation moving along a tube. It propels food along the digestive tube.
The walls of the ureter and urinary bladder are composed of layers of smooth muscle and connective tissue. Regular waves of muscle contractions in the ureters produce the force that causes urine to flow from the kidneys to the urinary bladder. Contractions of smooth muscle in the urinary bladder force urine from the bladder through the urethra. The Digestive System
discuss the action of digestive enzymes and the processes involved in digesting a well balanced meal;
identify the digestive organs and glands and discuss their functions;

summarise the exchange of fluids between the gut cavity and the blood system during each 24 hours of operation of the human digestive system;
low molecular weight through the stomach eg water, alcohol and aspirin
food stays in stomach for 2-4 hours
in the small intestine water soluble nutrients are absorbed into the hepaptic portal vein and transported to the liver and non-soluble nutrients are absorbed into lymphatic vessels and then into the blood
chime takes 5-6 hours to be processed
in the large intestine water, minerals and vitamins are absorbed
food takes 8-24 hours to pass through the large intestine
discuss metabolic rate and body temperature;
Body temp
- Humans can maintain body temp at 37° (homeotherms)
- Necessary to maintain normal enzyme function
- Heat loss = heat input
- Influenced by metabolism, exercise and environment
- Free energy = total amount of energy that can be liberated by complete catabolism of food
- 40% of energy released used for anabolism, muscle contraction and cellular activities
- 60% lost as heat
- Too hot or cold elicits a response
- 4 ways of heat exchange:
1. Radiation - The emission of energy as electromagnetic waves or as moving subatomic particles
2. Convection - transfer of heat from one place to another by the movement of fluids
3. Conduction - Energy transfer from one material to another by direct contact
4. Evaporation - process by which molecules of a liquid change state and become molecules of a gas
Increase in body temp
- Detected by receptors in the skin and hypothalamus
- Anterior hypothalamus responds
- Results in sweating vasodilation, and behavioural modifications (sitting in the shade instead of sun)
Decrease in body temp
- Detected by receptors in the skin and hypothalamus
- Posterior hypothalamus responds
- Results in shivering, vasoconstriction and behavioural modifications
Regulating metabolism
- 40% of energy consumed in food is incorporated into ATP
- 60% lost as heat energy

Production of ATP occurs via a series of biochemical reactions involving enzyme activity

Biol1003 Study Notes: Cells, DNA, Skeletal System, Study notes of Biology

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Biol1003 Learning Study Notes