Lecture 1 and 2 Flashcards
What are the characteristics that define life?
Cellular organisation Reproduction Metabolism Homeostasis Heredity Response to stimuli Growth and development Adaptation through evolution
How does the name of a species work?
First name is the name of the genus (capitalised) and then the second name is unique to the species within the genus
Evolution
Change in the genetic composition of a population from generation to generation
Change in the allele frequencies in a population over time.
What are the 3 domains of life
Bacteria, Archaea and Eukarya
Bacteria
Bacteria are microscopic, single-celled organisms that thrive in diverse environments. These organisms can live in soil, the ocean and inside the human gut. They are prokaryotes.
Archaea
Any of a group of single-celled prokaryotic organisms (that is, organisms whose cells lack a defined nucleus) that have distinct molecular characteristics separating them from bacteria as well as from eukaryotes
Eukarya
Eukarya are uniquely organisms whose cells contain a membrane-bound nucleus (eukaryotes, eukaryotic). They include many large single-celled organisms and all known non-microscopic organisms.
Prokaryotic cells
Cells that do no have a true nucleus or membrane bound organelles
Eukaryotic cells
Cells that contain a nucleus
Protists
Protists are a diverse group of organisms that are primarily microscopic and unicellular. Protists are eukaryotic which means they do have a nucleus and other membrane bound organelle. A protist is any eukaryotic organism that is not an animal, plant or fungi
Natural selection
Evolution occurs as the unequal reproductive success of individuals leads to adaptation to their environment, as long as their environment remains the same. This mechanism is known as Natural Selection
Where some phenotypes have the advantage in a certain environment, so individuals with that phenotype are more likely to survive, reproduce and pass on their alleles the next generation.
Who proposed natural selection?
Charles Darwin
Phylogenetic tree
A phylogenetic tree is a diagram that represents evolutionary relationships among organisms. Phylogenetic trees are hypotheses, not definitive facts. The pattern of branching in a phylogenetic tree reflects how species or other groups evolved from a series of common ancestors.
The root of the tree represents the ancestral lineage, and the tips of the branches represent the descendants of that ancestor. As you move from the root to the tips, you are moving forward in time.When a lineage splits (speciation), it is represented as branching on a phylogeny. When a speciation event occurs, a single ancestral lineage gives rise to two or more daughter lineages.
Adaptive radiation
This is a type of divergent evolution and it is the evolution from a common ancestor, of different forms adapted to different ecological niches which usually arises due to mass extinction or finding of new habitats
What are cells?
Cells are basic structural and functional units of every organism. There are two types of cells - Eukaryotic and Prokaryotic
Comparison between prokaryotic and eukaryotic cells - similarities
All bounded by a selective membrane (plasma membrane)
Inside the cell is a semi-fluid jelly-like substance = cytosol
All have chromosomes
All have ribosomes
Surface area to volume ratio
When cells grow its volume increases at a greater rate that its surface area therefore its SA:V ratio decreases
Small cells are more efficient at diffusion as they have a HIGH SA:V ratio
Cells may increase their SA:V ratio by having - long, thin and elongated cell shape, or folding the surface of the object/cell membrane
Plant cells are much larger than animal cells and they have large vacuoles which pushes the organelles to the edge of the cell where they get regular access to resources.
What is biomass?
The biomass is the mass of living biological organisms in a given area or ecosystem at a given time
Requirements of natural selection
Variation - individuals in a population vary one from another
Inheritance - Parents pass on their traits to their offspring genetically
Selection - Some variants reproduce more than others
Time - Successful variations accumulate over many generations
Condensed version… Variation in population Inhweritance between generations Selection by environment Time to accumulate variants
What is the tree of life?
The tree of life is a metaphor which expresses the idea that all life is related by common descent.
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Eukaryote cell range?
10-100μm
Prokaryote cell range?
Less than 5μm
Organelles (mitochondria and chloroplast) cell range?
1-10μm for mitochondria and 2-5μm for chloroplasts
Conversion of nanometers to microns
1nm = 0.001μm
What are nanometers used to measure?
Used to measure internal structures of cells and organelles
Membrane average measurement?
7-8nm
Ribosomes average measurement?
25nm
What events have Eukarya undergone that make us different
The origin of mitochondria - What appears to have happened is that during the evolution of eukaryotes, eukaryotes have formed a symbiosis with a type of bacteria called a proteobacteria and this symbiosis has led to a structure called a mitochondria
The origin of chloroplasts - Other particular eukaryotes (namely plants) have done the same thing with a cyanobacteria (photosynthetic bacteria) and they formed a chloroplast
These are not really evolutionary events, evolution has acted on them. This idea is known as the endosymbiosis theory.
Endosymbiosis
The endosymbiosis theory states that 2 key organelles in eukaryotes are derived from bacteria.
Mitochondria are derived from proteobacteria and chloroplasts are derived from cyanobacteria. These bacteria were engulfed by the ancestors of eukaryotes and tamed. This happened twice, first for mitochondria and then for chloroplasts.
How did mitochondria originate?
From a symbiotic relationship with a proteobacteria
How did chloroplasts originate?
From a symbiotic relationship with a cyanobacteria
Present or absent in eukarya, bacteria and archaea… nuclear envelope
Eukarya - Present
Bacteria - Absent
Archaea - Absent
Present or absent in eukarya, bacteria and archaea… membrane enclosed organelles
Eukarya - Present
Bacteria - absent
Archaea - absent
Present or absent in eukarya, bacteria and archaea… peptidoglycan in cell wall
Eukarya -absent
Bacteria - present
Archaea - absent
Present or absent in eukarya, bacteria and archaea… circular chromosome
Eukarya - absent
Bacteria - present
Archaea - present
Present or absent in eukarya, bacteria and archaea… growth in temperatures greater than 100 degrees Celsius
Eukarya - No
Bacteria - no
Archaea - some species can
Where are mitochondria said to have come from?
Proteobacteria
Where are chloroplasts said to have come from?
Cyanobacteria
What does evolution cause?
Results in vast diversity of past and present organisms
Comparison between prokaryotic and eukaryotic cells - differences
Location of DNA …
Eukaryote - Most DNA is in the nucleus which is bounded by a double membrane
Prokaryote - Most DNA is concentrated in a region called a nuclei which is not membrane enclosed
Interior of eukaryote and prokaryotes is known as the cytoplasm …
Eukaryote - Refers to only the region between the nucleus and plasma membrane. Variety of organelles within the cytoplasm suspended in cytosol.
Prokaryote - Most of these membrane bound structures are absent.
Eukaryotes are normally much larger than prokaryotes
Cell wall - in plants or animals? function?
Plant - Yes
Animal - No
Function - Protective outer layer of a plant cell that gives the cell strength and structure
Central vacuole - in plants or animals? function?
Plant - yes
Animal - no
Function - Provides internal support and the breakdown of waste products and hydrolysis of macromolecules
Centrosome - in plants or animals? function?
Plant - no
Animal - yes
Function - region where the cell’s microtubules are initiated
Chloroplast - in plants or animals? function?
Plant - Yes
Animal - No
Function - Site of photosynthesis, converts the energy of sunlight to chemical energy stored in sugar molecules
Nucleus - in plants or animals? function?
Plant - yes
Animal - yes
Function - holds genetic material for the cell and coordinates cellular activities
Plasma membrane - in plants or animals? function?
Plant - yes
Animal - yes
Function - phospholipid bilayer, boundary of a cell and forms a selective barrier
Flagella - in plants or animals? function?
Plant - No
Animal - yes in some cells
Function - locomotive organelle
Lysosome - in plants or animals? function?
Plant - no
Animal - yes
Function - Involved in digestion and waste removal (contains digestive enzymes)
Mitochondria - in plants or animals? function?
Plant - yes
Animal - yes
Function - site of cellular respiration and most ATP is generated here
Plasmodesmata - in plants or animals? function?
Plant - yes
Animal - no
Function - channels through cell walls that connect the cytoplasm of an adjacent cell
