cell mol module 1.1

Cell

the simplest and most fundamental unit of life

Cellular diversity

cells can differ greatly in size shape structure and function

Examples of cellular diversity

Lactococcus lactis Methanosarcinia blood cells dinosaur eggs Volvox aureus Purkinje neurons stomach epithelial cells and plant vascular elements

Are viruses cellular

viruses are raised as a question in the lecture because their status as cellular and living entities is debated

Microscope

an instrument that opened the way to understanding the cellular world

Robert Hooke

a scientist who studied cells using a microscope

Micrographia

Robert Hooke's book containing drawings in which the term cell was first used

Christopher White

the artisan who crafted Hooke's microscope

Antoni van Leeuwenhoek

the first person to see bacteria

Van Leeuwenhoek's microscope

a simple microscope containing a single lens with magnification of about 266x

Van Leeuwenhoek's observation

he observed bacteria in pepper-water

Van Leeuwenhoek's other observations

he studied microorganisms and also observed rabbit and dog sperm

Spontaneous generation

the belief that living organisms could arise from nonliving matter

Preformationism

an old belief about how life and organisms developed

Vitalism

the belief that living things possessed a special vital essence

Francesco Redi

a scientist who challenged spontaneous generation using rotting meat experiments

Redi's open jar

air and flies could enter and the meat developed maggots

Redi's closed jar

air and flies could not enter and the meat did not develop maggots

Redi's gauze jar

air could enter but flies could not and the meat did not develop maggots unless the gauze was broken

Conclusion of Redi's experiment

maggots came from flies rather than spontaneously appearing from meat

Vital essence idea

some scientists continued to believe that a vital essence in air was necessary for life

Cell theory

the theory that explains the fundamental cellular organization of life

Three principles of cell theory

all living organisms are composed of one or more cells the cell is the structural unit of life and all cells come from pre-existing cells

Omnis cellula e cellula

all cells come from pre-existing cells

Schleiden

one of the scientists associated with the development of cell theory

Schwann

one of the scientists associated with the development of cell theory

Virchow

the scientist associated with the principle that cells come from pre-existing cells

Louis Pasteur

the scientist who successfully challenged spontaneous generation using the swan-neck flask experiment

Pasteur's swan-neck flask experiment

an experiment showing that microorganisms did not arise from a vital essence in air

Swan-neck flask

the flask design allowed air to enter while preventing contaminants from reaching the nutrient broth

Cellular life

life that is organized into cells

Defining life

life is difficult to define because no single simple quality distinguishes living from nonliving things

Characteristics of cellular life

autonomy reproduction metabolism nutrition complexity organization growth and development information content permanence and change

HeLa cells

cancer cells donated by Henrietta Lacks that became an important model cell line

HeLa cell growth

HeLa cells can grow indefinitely when conditions remain favorable

Apoptosis

programmed cell death

Cellular complexity

living systems demonstrate a unique and complex molecular organization

Macromolecules

large biological molecules whose general structures evolved and stabilized early in the history of life

Hierarchical organization

nested levels of complexity that form cellular structures

Emergent properties

properties that arise from interactions among components and are not possessed by the individual components alone

Emergent properties and lower levels

higher-level emergent properties are influenced and restricted by lower levels of organization

Volvox colony

a colony containing Chlamydomonas-like cells daughter colonies cytoplasmic bridges intercellular gel reproductive cells and somatic cells

Genetic program

a heritable blueprint for life that also allows potential variation

Central dogma

the flow of genetic information used by cells to process genetic information

Genetic code

the system used to translate genetic information into functional products

Mutation

a change that can create variation in genetic information

Gene

the basic unit of heredity and a segment of DNA that provides instructions for proteins or functional RNA

Genome

all the DNA in a cell or organism

Gene expression

the process by which a gene is utilized according to genetic information processing

Cell division

the process by which cells grow and reproduce from pre-existing cells

Importance of cell division

cell division propagates species and maintains multicellular bodies

Diploid cell

a cell containing a larger paired amount of genetic material associated with maintaining multicellular organisms

Haploid cell

a cell containing a reduced amount of genetic material associated with reproduction

Energy in cells

cells require energy to maintain order

Autotroph

an organism that uses CO2 as its carbon source

Heterotroph

an organism that uses organic molecules as its carbon source

Phototroph

an organism that obtains energy from sunlight

Chemotroph

an organism that obtains energy from other sources such as chemicals

Aerobic

requiring oxygen

Anaerobic

not requiring oxygen and potentially using substances such as nitrite or sulphite instead

Spirogyra

a green filamentous alga that uses sunlight to power photosynthesis and is an autotroph

Hepatocytes

cells that are heterotrophs and rely on breaking down macromolecules for cellular reactions and energy

Complex chemical activities

cells perform many chemical reactions in different compartments

Enzyme

a molecule that increases the speed and efficiency of chemical reactions

RUBISCO

an enzyme involved in carbon fixation and described in the lecture as the most abundant protein on Earth

Metabolism

the many chemical reactions within cells that contribute to maintaining life

Homeostasis

the maintenance of a balanced internal physiological state

Catabolic reaction

a metabolic reaction involving the breakdown of molecules

Anabolic reaction

a metabolic or biosynthetic reaction involving the building of molecules

Metabolic pathway

a series of interconnected chemical reactions that work together for cellular function

Citric acid cycle

an example of an interconnected metabolic pathway

Mechanical activity

cellular activity that allows cells to change form or shape and perform movements

Cell movement

movement that is important for many biological activities and life processes

Kinesin

a molecular motor associated with movement along microtubules

Actin

a cytoskeletal component involved in cellular structure and movement

Microtubules

cytoskeletal structures involved in cellular mechanical activity

Irritability

the ability to perceive and respond to stimuli

Stimulus

a signal such as food temperature or chemicals that a cell can detect

Cell receptors

structures that allow cells to detect and respond specifically to their environment

Possible cellular responses

growth division movement changes in metabolic activity and cell suicide

Neutrophil

a white blood cell capable of chasing invading bacteria

Self-regulation

the ability of cells to maintain internal and external order

Cell fate

the developmental outcome of a cell

Sea urchin cell experiment

separated early cells can each develop into a whole although smaller sea urchin

Cell evolution

all cells are influenced by natural selection and can inherit changes that allow them to evolve

LUCA

the Last Universal Common Ancestor and the most recent common ancestor of all life on Earth

LUCA's significance

all currently living cellular lineages are believed to have descended from a common ancestral lineage

LUCA and first life

LUCA is not thought to have been the first life on Earth but rather the ancestor whose descendants survived to the present

Possible characteristics of LUCA

it may have been comparable to modern prokaryotes and probably anaerobic and acetogenic

Possible habitat of LUCA

high-temperature water near deep-sea vents close to ocean-floor magma flows

Early Earth

Earth had harsh conditions including a reducing atmosphere high energy and possible heavy meteor impacts

Reducing atmosphere

an early Earth atmosphere described in the lecture as one of the harsh conditions faced by early life

Late Heavy Bombardment

a period of heavy meteor impacts associated with early Earth conditions

Early cellular life

the first cells may have resembled prokaryotic microbes

Acidocalcisome

an acidic vacuolar organelle with high phosphorus concentration

Exobiology

the study of life in environments relevant to the origin or existence of life

Theory of cellular evolution

a proposed sequence involving abiotic formation polymerization protocell enclosure molecular selection and cellular evolution

Evidence for early life

prokaryotic microfossils have been found in stromatolites

Stromatolites

structures containing evidence of ancient microbial life

Abiotic formation

the formation of organic molecules from nonliving chemical processes