IB Biology HL Y2 U3: Anatomy & Physiology

Cell Theory

A fundamental concept in biology that states all living organisms are composed of cells, that cells are the basic unit of life, and that all cells arise from pre-existing cells.

deductive reasoning

A logical process where conclusions are drawn from general principles to specific cases, used to derive hypotheses based on established theories.

electron microscopy

A technique that uses a beam of electrons to illuminate a specimen, allowing for high-resolution imaging of cellular structures at the nanoscale.

cryogenic EM

A variant of electron microscopy that uses extremely low temperatures to preserve and visualize biological specimens in their native states, enhancing imaging quality and detail.

freeze fracture EM

A method in electron microscopy that involves cooling a specimen to very low temperatures, then fracturing it to reveal internal structures, allowing for detailed visualization of cellular membranes.

fluorescence stains and immunofluorescence

Techniques used in microscopy that utilize fluorescent dyes to label specific cellular structures or proteins, enabling visualization under specific wavelengths of light.

features shared by all cells

include a plasma membrane, cytoplasm, ribosomes, and genetic material (DNA). These structures facilitate essential cellular functions and processes.

prokaryote cell structure

Prokaryote cell structure refers to the simpler and smaller organization of cells lacking a nucleus and membrane-bound organelles. Key features include a cell wall, plasma membrane, cytoplasm, ribosomes, and sometimes plasmids and flagella.

parts of prokaryote

cell wall

cytoplasm

plasma membrane

nucleoid region: single circular chromosome w DNA

flagellum: locomotion

pili: allow cell to adhere t surfaces and exchange DNA

70s ribosomes

bacillus bacteria

red shaped

has flagella and pili

gram positive

staphylococcus

gram positive

spherical

no flagella and pili

eukaryote cell structures

plasma membrane

cytoplasm

nucleus: chromosomes, double membrane, pores

rough ER: protein synthesis

golgi

80s ribosomes

chromosomes: DNA around histones

mitochondria

vacuole

lysosome: large molecules digestion

smooth ER: lipid synthesis and detox

cytoskeleton: made of microtubules and microfilaments

processes of life

homeostasis

metabolism

nutrition

movement

excretion

growth

response to stimuli

reproduction

multinucleate atypical cells

aseptate fungal hyphae and skeletal muscle

no nuclei atypical cells

red blood cells and phloem sieve tube elements

stem cells

undifferentiated and endlessly reproducing cells

basis for stem cell differentiation

diff gene expression pattern triggered by change in environmentleading to specialized functions.

meristematic tissue

plant tissue containing stem cells

efficient resource use, large size, longer life span, range of function, consumption of smaller organisms

2 ways to calibrate microscope

eyepiece graticule

stage micrometer

resolution

ability of a microscope to distinguish details of a specimen/sample

magnification equation

(image length)/(actual length)

cm to mm to um to nm

x10

x1000

x1000

calculating magnification

measure length of scale bar

note actual length of scale bar

input image length and actual length into magnification

cel differentiation

occurs by gene expression

differentiation of stem cells

embryonic stem cells diff into spec cell/tissue

morphogens

gene regulating chemicals released from embryo cells

spread and make conc gradient w more near source

bind to receptors causing gene expression

conc decides type of spec cell

stem cells

undifferentiated, unlimited capacity to divide, can diff into spec

stem cell niche

locations in body where stem cells are maintained/promoted to proliferate/differentiate

bone marrow (ex of stem cell niche)

niche for hematopoietic stem cell

diff into blood cell

hair follicles (stem cell niche ex)

have epithelial, melanocyte, mesenchymal stem cells

self review, diff, region hair growth, maintain skin homeostasis

3 types stem cells

totipotent

pluripotent

multipotent

totipotent

can diff into all cell types and develop into embryo

ex of totipotent

zygote

pluripotent

can diff into all cell types but not into embryo

ex of pluripotent

embryonic stem cell

multipotent

can diff into limited range of cells

ex of multipotent

adult stem cellfound in various tissues

specialized human cells (6)

1. sperm: smallest cell, L of 50-70um, W = 2-3um

2. ova (egg): largest volume, D = 100um

3. neuron: specialized for transmitting signals, with a long axon and branching dendrites

4. red blood cell: diameter = 6-8um for capillary travel

5. white blood cell: 6-20um depending on type

6. Striated muscle fibers: atypical multinucleate cells from fusion of diff cells, L range of mm-cm, diameter 10-100um

what does SA represent

plasma membrane

what does volume rep

cytoplasm

inc object size =

inc metabolism rate > inc rate of transfer materials in and out

when do cells divide

when SA isn’t efficient for exchange materials for metabolism

adaptations for SA:V for red blood cells (ethryocytes)

Red blood cells (erythrocytes) have a biconcave shape to increase surface area for oxygen exchange, lack a nucleus to maximize space for hemoglobin, and are flexible to fit through capillaries.

adaptations for SA:V for cells lining proximal convoluted tube in nephron of kidney

The cells lining the proximal convoluted tubule have microvilli to increase surface area for reabsorption, numerous mitochondria for energy production, and tight junctions to maintain a selective barrier.