Week 11 Flashcards
Name characteristics of living things
- Have an Organized Structure
- Are Composed of Organic Molecules and Cells
- Grow and Reproduce (on their own!)
- Respond to the Environment and its Changes
- Have a Metabolism
◦ Take in Food
◦ Excrete Waste
◦ Maintains Homeostasis - Evolve and Adapt
Difference in prokaryote and eukrayotes accoridng to DNA , organelles, reproduction, average size
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DNA:
- Prokaryotes: DNA is “naked” (not bound to proteins), circular, and usually lacks introns.
- Eukaryotes: DNA is bound to proteins, linear, and usually contains introns.
-
Organelles:
- Prokaryotes: No nucleus; no membrane-bound organelles; 70S ribosomes.
- Eukaryotes: Has a nucleus; membrane-bound organelles; 80S ribosomes.
-
Reproduction:
- Prokaryotes: Reproduce through binary fission; have a single chromosome (haploid).
- Eukaryotes: Reproduce through mitosis and meiosis; chromosomes are paired (diploid or more).
-
Average Size:
- Prokaryotes: Smaller (~1–5 µm).
- Eukaryotes: Larger (~10–100 µm).
This chart is a helpful summary for distinguishing these two types of cells.
What are the 4 major macromolecules and monomers prokaryote and eukaryote cells rely on ?
-
Protein
- Monomer: Amino acids
-
Nucleic Acids (DNA, RNA)
- Monomer: Nucleotides
-
Fats (Lipids)
- Monomer: Glycerol and fatty acids
-
Carbohydrates (Complex sugars)
- Monomer: Simple sugars (monosaccharides)
These macromolecules and their monomers play critical roles in the structure and function of cells across both cell types.
Monomer
(“one-part”): a small molecule that can covalently bind
to other similar molecules to form a larger molecule, called a macromolecule
◦ For example – amino acids, monosaccharides, nucleotides, fatty acids and glycerol
Polymer
Large number of monomers boded together
Macromolecule
Any very large organic molecule, usually made up
of smaller molecules called monomers that join together into a polymer. The main macromolecules are proteins, nucleic acids (DNA/RNA), and polysaccharides (e.g., starch, cellulose)
How did Eukaryotes airse
Endosymbiosis
Explain endosymbiosis
- Start with two independent bacteria.
- One bacterium engulfs the other.
- The engulfed bacterium begins to live inside the other.
- Both bacteria benefit from the arrangement—the internal bacterium provides additional functions, like energy production.
- The internal bacteria are passed on from generation to generation as part of the host cell, leading to the evolution of organelles like mitochondria and chloroplasts in eukaryotic cells.
This mutual relationship led to the development of complex eukaryotic cells from simpler prokaryotic ancestors.
Where did chloroplastes come from
Endosymbiosis
When did life originate
3.5 Billion years ago
When did the earliest fossils emerge and what is it
3.45 Billion YO
* Evidence from microfossils and stromatolites found in S.Africa and Australia
* Produced by mainly photosynthesizing bacteria…
* But even these were relatively complex compared to the earliest precursor molecules
What fundamental property of the universe does life defy
Entropy
What is entropy
The universal tendency towards disorder
Creating order from disorder requires inputs of…
…energy
Chemical evolution
Inputs of energy lead to the formation of increasinly complex carbon contaning substances
WOOHO
!!!!
4 Macromolecules of life
Carbohydrates
Lipids
Proteins
Nucleic acids
The macromolecules: DNA and RNA are polymers,
specifically nucleic acids, made up of many nucleotides
Deoxyribonucleotides for DNA
Ribonucleotides for RNA
Nitrogenous bases
Molecules that help to make up nucleotides
Which nitrogenous base is only found in RNA
Uracil found only in RNA, replaces thymine in RNA
What are functional enzyme like 3d strands called
Ribozymes
How are 3d rna strands formed
Long chains of RNA will fold back and basepair with themselves, forming 3-D structures, like proteins.
Natural seelction of RNA sequences
- There is variation in a
population of RNA molecules. - RNAs that perform a
particular job are more likely to
be selected than others.
Selected RNAs are promoted to
reproduce more than others. - The population of RNA
has evolved and now
contains more useful
molecules.
A living thing must ___ to avoid decay and disorder
Work
Why was RNA probably the original form of life ?
It serves as a template for its own reproduction.
How does RNA reproduce
RNA has the feature of base complementarity. Nucleic acids form the backbone of the strand, and purines and pyrimidines selectively pair together via hydrogen bonds to create a complementary strand.
What is the basic requirement for life
Reproduction
What fundamental drive does the innate ability of RNA and DNA to replicate itself create in terms of natural selection, and how does this affect the prevalence of certain sequences?
The innate ability of RNA - and thus DNA – to replicate itself means that there is a fundamental drive for natural selection to favor those sequences which are most likely to reproduce themselves.
The more capable a strand is of reproducing, the more there willbe of it!
How does natural selection operate on individuals, and what is the impact on the gene pool for those who do not reproduce?
Individuals who do not reproduce drop out of the gene pool - biologically speaking, they contribute nothing to their species.
Natural selection operates on the traits (phenotypes) of individuals; those individuals with the most successful phenotypes have the most offspring.
Because traits are ultimately determined by an individual’s genes (DNA), natural selection promotes certain genotypes.
More offspring = more DNA replication = life WIN!
So what is the purpose of life
reproduction
Fitness in relation to the purpose of life
The genetic contribution of an organism’s descendants
to future generations. (e.g. number of surviving offspring).
The “goal” of life is to produce as many healthy offspring as possible, and to equip them such that their likelihood of reproductive success is maximized as well.
Fitness is only compared relative to individuals of the same species, and usually in the same population.
So technically the purpose of life is: High Relative Fitness!
High relative fitness =
having lots of babies (biologically speaking)
Asexual reproduction
Binary fission
Single parent cell doubles its DNA, then divides into two cells. Usually occurs in bacteria.
Asexual reproduction
Budding
Miniature adult grows on surface of parent breaks off, resulting in the formation of two individuals. Occurs in yeast and some animals
Asexual reproduction
Fragmentation
Organisms break into two or more fragments that develop into a new individual. Occurs in many plants, as well as some animals
Asexual reproduction
Parthenogenesis
An embryo develops from an unfertilized cell. Occurs in invertebrates, as well as in some fish, amohibians, and reptiless
Explain sexual reproduction
Each parent contributes a gamete - a sex cell that has half of the normal DNA of a regular body cell. In males, the gametes are sperm and in females, the gametes are eggs.
When these two gamete combine during fertilization, the result is a zygote, which then continues to develop into an embryo.
Aseual reproduction is essentially..
cloning
What is the original form of reproduction
Asexual reproduction
NAme some positive things about asexual reproduction
100% of your genes passed! Why give up 50%??
Preserve successful genotypes! Don’t dilute with recombination and recessive traits!
No mate required; don’t need others around
NAme the problems of sexual reproduction
1) In a sexual population, half the individuals cannot technically reproduce – the males!
2) All offspring inherit only 50% of each parent’s DNA
When did life begin
explanation
Life began the moment molecules of information began to reproduce and evolve by natural selection
4 Requirements for life
- A living thing must work to avoid decay and disorder.
- To do that, a living thing must have or create a closed system (a cell)
- They have some molecule that can carry information.
- This information must evolve by natural selection
