Exam 2 bio114

Protist

diverse group of mostly eukaryotic organisms that do not fit neatly into the traditional plant, animal, or fungi groups

Eukaryotic

cells have nucleus and membrane-bound organelles

Unicellular

consisting of one cell

multicellular

consisting of many cells

metabolic diversity

protists can obtain energy in many different ways

photoautotroph

uses light energy to make organic molecules from inorganic carbon

Photoheterotroph

uses light for energy but obtains organic carbon from the environment

chemoheterotroph

obtains both energy and carbon from organic molecules

chemoautotroph

an organism, typically a bacterium, which derives energy from the oxidation of inorganic compounds

mixotroph

can use more than one nutritional strategy, such as photosynthesis and consuming organic molecules

convergent evolution

unrelated organisms independently evolve similar traits because they experience similar environmental pressures

Fungi and oomycetes

example of convergent evolution because they have similar fungus-like characteristics despite not being closely related

Oomycete

fungus-like protist. Irish potato famine caused by Phytophthora infestans, an oomycete. This was devastating because potatoes were a major food source.

Trypanosoma

parasitic protist that causes diseases including African sleeping sickness and Chagas disease.

African sleeping sickness

caused by Trypanosoma brucei and transmitted by tsetse flies.

Chagas disease

caused by Trypanosoma cruzi and commonly transmitted by triatomine (“kissing”) bugs.

Malaria

disease caused by Plasmodium, a parasitic protist

Malaria vector

female Anopheles mosquitoes

Plasmodium

parasitic protist responsible for malaria

Malaria prevention

reducing mosquito bites and mosquito populations; examples include insecticide-treated bed nets and vector control.

why malaria is difficult to treat

Plasmodium has a complex life cycle and can develop resistance to drugs.

Why malaria vaccines/treatments are difficult

the parasite changes through different life stages and can evade immune responses.

Antibiotic/drug resistance

resistance that becomes more common in a population because resistance individuals survive treatment and reproduce

Insecticide resistance

same evolutionary principle occurring in mosquito populations

natural selection

individuals with traits that increase survival/reproduction leave more offspring, causing those traits to become more common.

important misconception

The drug/insecticide does not cause an individual to evolve resistance during its lifetime.

Correct idea: Variation in resistance already exists in the population; the environment selects for individuals with advantageous resistance traits.

Wolbachia

bacterium that lives symbiotically inside many arthropods

Wolbachia and malaria — wolbachia can make mosquitoes more resistant to Plasmodium infection

Primary producer

organism that produces organic molecules from inorganic materials, usually through photosynthesis

photosynthesis

process that uses light energy to produce organic molecules and releases oxygen

Phytoplankton

photosynthetic organisms that drift in aquatic environments.

Diatoms

photosynthetic protists that are major aquatic primary producers

Dinoflagellates

photosynthetic protists that are important aquatic primary producers.

coral bleaching

loss of symbiotic algae from coral, causing coral to lose color and often become stressed.

Cause of coral bleaching

environmental stress, especially increased ocean temperatures.

Limiting nutrient

nutrient whose scarcity restricts population growth

nitrogen

needed for proteins and nucleic acids

phosphorus

important in nucleic acid, ATP, and phospholipids

nutrient enrichment

increased nutrient availability that can increase algal/phytoplankton growth

Fertilizer runoff

nitrogen and phosphorus from agricultural fertilizers entering waterways

Harmful algal bloom (HAB)

rapid growth of algae/phytoplankton that can negatively affect ecosystems and organisms

eutrophication

nutrient enrichment or an aquatic ecosystem that can cause excessive algal growth

hypoxia

abnormally low oxygen concentration

Dead zone

area of water with very low oxygen where many organisms cannot survive

basic dead-zone sequence

Fertilizer runoff → increased N/P → increased phytoplankton → phytoplankton die → decomposition increases → decomposers use O₂ → hypoxia → organisms die/leave

Evolution

change in heritable characteristics of a population across generations

• Important distinction: An individual/population changing its behavior or growth rate in response to the environment is not necessarily evolution.

• Increased nutrient availability causing algae to reproduce faster = environmental response, not evolution.

Nucleotide

monomer of nucleic acids

nucleotide components

1. 1. sugar

2. 2. phosphate group

3. 3. nitrogenous base

DNA sugar

deoxyribose

RNA sugar

ribose

DNA bases

A, T, C, G

RNA bases

A, U, C, G

DNA base pairing

A-T and C-G

RNA base pairing

A-U and C-G

Chromosome

DNA molecules associated with proteins that contains genetic information

Chromatid

one copy of a duplicated chromosome

Sister chromatids

identical copies of a chromosome produced during DNA replication

they are counted as one chromosome while they are attached

Homologous chromosomes

chromosome pair containing the same genes in the same locations, with one chromosome inherited from each parent

Centromere

region where sister chromatids are joined

Origin of replication

Location where DNA replication begins

Helicase

Unwinds DNA and breaks hydrogen bonds

Single-strand binding proteins

Keep DNA strands separated

Primase

Makes RNA primers

DNA polymerase

Adds DNA nucleotides to the new strand

Ligase

Joins DNA fragments together

RNA primer

short RNA sequence needed to start DNA synthesis

Okazaki fragments

short DNA fragments made on the lagging strand

Semiconservative replication

each new DNA molecule contains one original strand and one newly synthesized strand

Antiparallel

DNA strands run in opposite directions: one 5’→ 3’ and the other 3’→ 5’

Leading strand

synthesized continuously

Lagging strand

synthesized continuously

DNA polymerase direction

adds nucleotides to the 3’ end, so new DNA is synthesized 5’→ 3’

DNA proofreading/repair

mechanisms that identify and correct replication errors

DNA sequencing

determines the nucleotide sequence of DNA

PCR

makes many copies of specific DNA sequence

Gel electrophoresis

separates DNA fragments based primarily on size

Cell cycle

G1 → S → G2 → M → Cytokinesis

G1

cell grows and performs normal functions

S phase

DNA is replicated

G2

cell prepares for division

M phase

mitosis/karyokinesis

Prophase

chromosomes condense; spindle forms; nuclear envelope breaks down

Metaphase

chromosomes line up in the middle of the cell

Anaphase

sister chromatids separate

Telophase

chromosomes reach opposite pole and new nuclei form

cytokinesis

cytoplasm divides into two cells

karyokinesis

division of the nucleus

single-celled eukaryotes

can use mitosis for asexual reproduction

multicellular organisms

growth, development, and tissue repair/replacement

result of mitosis

two genetically similar/identical daughter cells with the same chromosome number as the original cell

Binary fission

common form of cell division in prokaryotes

associated with asexual reproduction and produce daughter cells.

Mitosis

nuclear division in eukaryotic cells

associated with asexual reproduction and produce daughter cells.

Proteins

Amino acid — monomer

20 amino acids — standard amino acids used to build proteins.

R-group — variable portion of an amino acid that determines its properties.

Nonpolar amino acid — hydrophobic; tends to avoid water.

Polar amino acid — hydrophilic; interacts with water.

Charged amino acid — electrically charged and generally hydrophilic

Shape determines function

Primary structure

amino acid sequence

secondary structure

local structure such as α-helices and β-sheets

tertiary structure

overall 3D shape of one polypeptide

Quaternary structure

interaction of multiple polypeptide subunits

Transcription

DNA → mRNA, production of RNA using DNA as a template.

• Location in eukaryotes — nucleus.

• RNA polymerase — enzyme that builds RNA.

• Template strand — DNA strand used to make RNA.

• Coding strand — DNA strand with the same sequence as mRNA except DNA has T where mRNA has U.

• mRNA — carries genetic information from DNA to ribosome.

• mRNA synthesis direction — 5' → 3'.

Translation

mRNA → protein, process of using mRNA information to make a polypeptide

• Location — ribosomes in cytoplasm or associated with rough ER.

• Codon — three-nucleotide sequence on mRNA that specifies an amino acid or stop signal.

• Anticodon — three-nucleotide sequence on tRNA that pairs with an mRNA codon.

• tRNA — carries a specific amino acid to the ribosome.

• rRNA — major structural/catalytic component of ribosomes.

• Ribosome — site of translation.

Genetic code

• Triplet code — three RNA nucleotides form one codon.

• Universal — nearly all organisms use the same genetic code.

• Redundant — multiple codons can code for the same amino acid.

• Unambiguous — each codon specifies only one amino acid or stop signal.

• Start codon — AUG.

• Methionine — amino acid specified by AUG.

• Stop codons — UAA, UAG, UGA

free ribosome

produces proteins that remain in the cytosol