TrentU - Foundations of Cellular and Molecular Biology (Sc)
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Course
Fdns of cell and molecular biology (BIOL1030)
Institution
Trent University (TrentU
)
Notes taken during the lecture; used as an extension to lecture notes. Includes easier to digest wording of key concepts and additives said verbally by the professor.
Lecture 1:
Introduction to Homeostasis
● Positive feedback inhibition: amplifies change
○ ex/ vomit (you vomit others vomit) & birth
● Negative feedback inhibition: reduces change
● Conformer (cannot homeostasis) example: squid and octopus
○ Value of internal and external variable are the same
● Regulator example: humans
○ Try to maintain internal environment in spite of external environment
● Environmental change:
○ Minutes to hours → physiological adjustment
○ Weeks to months → acclimatization
○ Geological time → evolutionary change
Lecture 2:Physiological Control
● Pancreas = sensor (senses insulin levels) + effector (responds)
● Sum in time: rapid signals
● Sum in space: many together
● All we are ever doing is transmitting action potentials
○ The firing rate/speed of action potentials indicate to the brain if touching light or
hard (same with strong/faint smell)
○ Speed at which action potential is transmitted
● Afferent = arrive at brain Efferent = exit brain
Lecture 3: Respiration and Circulation
● Diffusion = need thin membrane and large SA
● Gill filament (lamellae) increase SA
● Water goes in opposite direction of blood = countercurrent blood flow
○ Maximizes uptake of oxygen
● Unidirectional - goes through the lung in only one direction (unlike humans, like birds)
○ The two inhalations and exhalations occur at the same time
○ No stale air left (thus more efficient)
● Unidirectional flow is more efficient than tidal ventilation
● The concentration of air in the lungs is lower than that in the environment
○ b/c we breathe in fresh air that mixes with stale air (tidal ventilation)
Lecture 4: Animal Movement
● 1 myosin surrounded by 6 actin
● If a skeletal muscle is no longer able to make enough ATP, then actin and myosin in the
sarcomere will remain bound (ex/ Rigor Mortis)
● Actin slides relative to myosin (sliding filament theory)
● No overlap - at long muscle lengths
● Most overlap - at medium muscle lengths
● Too much actin interference - at short muscle lengths
Lecture 5: Animal Immune System
● IgA: advantage = in breastmilk
, Lecture 6: Cell Division & DNA Replication
Cell division
● The process by which cells make more cells
● Occurs for growth, healing, reproduction, cell replacement
● In prokaryotes occurs by binary fission
● In eukaryotes occurs by mitosis
● Eukaryotic gametes (sex cells) are produced by meiosis
Cell division through cell cycle (Eukaryotes)
● Two stages: M phase and Interphase
Interphase
● Lasts 10-14 hours preparing for division including nuclear DNA replication and increase
in cell size
● G1 phase: size and protein content of cell increases
● S phase: entire nuclear DNA content is replicated
● G2 phase: preparation for mitosis and cytokinesis
● G0 phase: no active preparation for cell division - present in cells that do not actively
divide
Mitosis 5 Phases - things to remember!
1. Prophase: chromosomes condense and become visible
2. Prometaphase: chromosomes attach to mitotic spindle
3. Metaphase: the chromosomes align
4. Anaphase: sister chromatids fully separate
5. Telophase: nuclear envelopes reform around newly segregated chromosomes
Meiotic Cell division
● Results in 4 daughter cells
● Each contains ½ the # of chromosomes as the parent
● Each is genetically unique (b/c crossing over + independent assortment)
Meiosis 1 - 5 things to remember
1. Prophase:
Meiosis 2 - 5 things to remember (like mitosis)
Cancer
● Proto-oncogenes: normal genes important in cell division that have the potential to
become cancerous if mutated
● Oncogene: cancer-causing gene
● Tumor suppressors: gene that encode proteins whose normal activities inhibit cell
division
DNA Replication
● DNA replication is the process of duplicating a DNA molecule
● Each parental strand is a template for the daughter strand
● DNA replication is semiconservative - new double strand that occurs is created from
template (conserved) and daughter (generated)
● A and T are held together by two hydrogen bonds
● G and C are held together by three hydrogen bonds - harder to break apart
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