Biology Midterm Exam

This overviews the three topics #1 Evoloution, #2 Lipids and Membrane Dynamics, and #3 Carbohydrates and Cell Structures

What are the unifying themes of biology?

• Evolution

• Organization

• Information (genetic)

• Energy

• Interactions

Evolution

Through natural selection, species are able to adapt and survive to their environments.

Organization

Structures fit functions, which is in a species organization

Information

Genetic information, which is encoded in DNA, determines the appearance of a species

Energy

Energy flows one way from sun → plants → herbivore →carnivore … etc.

Matter cycles between species and environment.

Interactions

Within a system, species intract with other species and its enviroment

• ex: prey and preditor

Properties of Life

• Order

• Evolutionary Adaptation

• Regulation

• Energy Processing

• Growth and Development

• Response to the Environment

• Reproduction

Order

In a species, a highly ordered structure characterizes life.

Regulation

Regulation in a species, such as blood flow, water intake, etc.

• helps maintain equilibrium

Evolutionary Adaptation

Adaptations evolve over generations by reproductive success of individuals with heritable traits which is best suited for their environments.

Reproduction

Organisms reproduce their own kind.

Response to the Environment

Organisms respond to stimuli (environmental)

• ex: Venus flytrap closing to a bug being on its sensory portions of the plant, indicating food present.

Growth and Development

Inherited information carried by genes controls the pattern of growth and development in an organism.

Energy Processing

Obtaining “fuel” from something to use for regular functions

• ex: eating before a run

Reductionism

Reducing complex systems to simpler components that are more manageable to study.

• Powerfull strategy in Biology

Levels of Biological Organization

• Biosphere

• Ecosystems

• Communities

• Population

• Organisms

• Organs

• Tissues

• Cells

• Organelles

• Molecules

Biosphere

Consists of all life on Earth and places where life exists

• most regions of land

• most bodies of water

• the atmosphere to an altitude of several kilometers

• sediments below the ocean floor

Ecosystems

Consists of all living things in a particular area and all the nonliving components which life interacts with

• ex: soil, water, atmospheric gases, light.

Communities

Array of organisms living in a particular ecosystem

• Each forms of life belongs to a species

Populations

Consists of a species living within the bo9unds of a specified area

Organisms

Individual living things

• ex: plant, animal, fungus, and bacterium..

Organ

A body part that is made up of multiple tissues and has specific functions in the body.

Tissues

A group of cells that work together, preforming a specific function.

Cells

Life’s fundamental unit of structure and function. Some have and are just one, others multiple.

Organelles

Various functional components present in cells (essentially the cell’s organs)

Molecules

A chemical structure consisting of two or more units called atoms.

Emergent Properties

Emerge from the arrangement and interaction of parts within a system

• not unique to life

Novel Properties

Emerge at each level that are absent from the proceeding one.

• ex: photosynthesis occurs in chloroplasts in plants, but wont occur in a test tube

Systems Biology

Exploration of a biological system by analyzing the various interactions between its parts.

• Can be used to study life at all levels

• Enables biologists to pose new questions

Are structure and function correlated at all?

Yes, structure and function of living organisms closely related.

The Cell theory

#1. All organisms are composed of one or more cells

• Schleiden and Schwann (1838-39)

#2. The cell is the basic unit of life

• Schleiden and Schwann (1838-39)

#3. All cells are produced by the division of preexisting cells

• Virchow (1858)

All Cells…

• Enclosed in a membrane

• Use DNA as their genetic information

Eukaryotic cell

Has a membrane-enclosed organelles and is normally complex

• largest is usually the nucleus

• Typically big and round

Prokaryotic cell

Simpler, usually smaller, and doesn’t contain membrane-enclosed organelles.

• has no nucleus

What type of cell is this?

Eukaryotic

What type of cell is this?

Prokaryotic

Chromosomes contain what?

Most of the cell’s DNA (deoxyribonucleic acid)

The ability of cells to divide is the basis of ….

• All reproduction

• growth and repair

(Of multicellular organisms)

Genes

• Contain information required for the synthesis of polypeptide chains and proteins within cells

• Each chromosome has hundreds or thousands of

DNA function

• Inherited by offspring from parents

• Controls the development and maintenance of organisms

DNA structure

• Made of two long chains that are arranged in a double helix

• Each chain is made of chemical building blocs

• These blocks are called nucleotides (A, G, C, T)

Gene Expression

The information in genes directs the manufacturing of cellular products in genes in this process…

In gene expression…

• DNA is transcribed → RNA

• RNA is translated → protein

Protien’s role in gene expression

It is involved in building, maintaining and preforming activities.

Genome

Organism’s entire set of genetic instructions.

Genomics

Study of whole sets of genes within and between species

Proteomics

Study of all the proteins encoded by a genome (called proteomes)

The Genomic approach depends on…

• High technology → yields enormous amounts of data

• Bioinformatics

• Collaboration between interdisciplinary research teams

Bioinformatics

The use of computational tools to process a large volume of data

The input of energy from the sun and transformation of energy from one form to another make life…

Makes life possible.

When organisms use energy to preform work what type of energy is lost to the surroundings?

Heat energy

Energy flows through an ecosystem.. what does energy enter and exit as?

Light → Heat

Cells are able to coordinate various chemical pathways through what type of regulation?

Feedback Regulation

Feedback regulation

• The output/product of a process that regulates that very process

• Allows biological process to self-regulate

• Common to all forms of life

Negative Feedback

The responce reduces the inital stimulus

• Most common in living systems

Positive Feedback

Enhances initial stimulus

Interactions

• Every organism interacts with other organisms and its environment ( including non-living factors)

• Organisms and their environments are influenced

• May be beneficial or harmful

Human Interactions

• With the environment can result in harmful consequences

• Generated CO2 stays in the atmosphere and contributes to major issues such as global warming

  • Global Warming is a major aspect of global climate change.

Why are there differences among species?

It is due to the accumulation of heritable changes.

• Evolutionary mechanisms account for the unity and diversity of all species on Earth.

How many species have been identified and named to date?

1.8 million species.

• Each year thousands more have been discovered

Each species is given a two-part name. How is the name formed? (What are the two components, list them in order)

#1. The name of the genus

#2. Unique to the species within that genus

What is the total number of species on Earth?

Around 10 million to over 100 million range.

Taxonomy

Branch of biology that names and classifies species into groups in an specific order.

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

What are the three domains?

• Domain Bacteria

• Domain Archaea

• Prokaryotic organisms

  • Domain Eukarya (Eukaryotic organisms)

What are the four subgroups of domain Eukarya?

• Includes four subgroups

  • Kindom Plantae → Produce food via photosynthesis

  • Kindom Fungi → Absorb nutrients

  • Kindom Animalia → Ingest other organsisms as food (Herbivore, Carnivore, Omnivore)

  • Protisits (now split into several kindoms0 → Mostly single-celled, and are the most abundant eukaryotes

Domain Eukarya consists of…

• Autotrophs

• Heterotrophic fungi

• Multicellular organisms that ingest other organisms

• Mostly unicellular organisms and simple multicellular organisms

Autotrophs

Multicellular photosynthesizing land plants (make their own food).

Heterotopic

Absorb nutrients from outside.

What is the unity that underlies the diversity of life?

• DNA is the universal genetic common to all organisms

• In many structures of the cell, is found to be common

Charles Darwin

• Published “The Origin of Species by Means of Natural Selection”

• Theory explained the duality of unity and diversity

• He made two main points

  • Decent with modification from common ancestors

  • Natural selection is the mechanism for decent with modification

• Made observations, inferred, and named a process called Natural Selection

What was Charles Darwin’s Observations?

• Individuals vary in traits, many of which are heritable

• More offspring are produced than survive, competition is inevitable

• Generally, species suit the environment they are in

What did Charles Darwin infer?

• Those that are best suited to their environment are likely to survive, and reproduce.

• Over time, individuals in a population will have advantageous traits

Why does evolution occur?

Due to the unequal reproductive success of individuals.

What does natural selection result in?

The adaptation of organisms to their environment.

The tree of life

• Evolutionary relationships are often illustrated with a tree-like diagram, which starts with a common ancestor, branching off to the descendants.

• Can be seen in body parts aswell

  • The forelimbs of a human, bat, horse etc. share a common skeletal architecture

• Same structures, but have different functions

• Fossils prove decent with modification

Evolution

Can be defined using “Decent with Modification” - Charles Darwin

Fossils

The remains/traces of organisms from the past

• Typically found in sedimentary rock, appearing in layers of strata

Provide evidence (records)

• The orgin, extinction and changes of species

Paleontology

Study of fossils

• largely developed by Georges Cuvier (French Scientist)

• Each boundary between strata was a sudden catastrophic event

What was Landmark’s hypothesis of evolution?

• Species evolve through use and disuse of body parts and inheritance of acquired characteristics (later debunked)

  • ex: appendix; we have it but no longer use it

Charles Darwin’s voyage

• Took place on the SMS Beagle

• 5-year around the world voyage

• He collected specimens of South American plants and animals

• Observed fossils resembled living species from nearby region

• Observed the uplift of rocks

• Went to the Galapagos Islands

Adaptations

Inherited characteristics of organisms that enhance their survival and reproduction in specific environments.

Origin of Species - Darwin and his three broad observations

• Unity of life

• Diversity of life

• The match between organisms and enviorment

Artificial Selection

Humans modify other species by selecting and breeding individuals with desired traits

Darwin’s Observation and Inferences (there are two of each)

• Observation #1: Members of a population vary in inherited traits

• Observation #2: Species can produce more offspring than environment can support, which many offspring fail and die

• Inference #1: Inherited traits give a higher probability of surviving and reproducing in a given environment, which tend to leave more offspring

• Inference #2: Unequal ability of individuals to survive and reproduce lead to accumulation of favorable traits over generations

Key features of natural selection

• Individuals don’t evolve; populations evolve over time

• it can only increase/decrease heritable traits that vary in a population

• Adaptations vary across different environments

• Increases the frequency of alleles that enhance survival and reproduction

What are the four types of data that document the pattern of evolution?

• Direct observations

• Homology

• Fossil record

• Biogeography

Evolution of Drug-Resistant Bacteria

• Staphylococcus aureus (S. aureus): commonly found on people

• MRSA: a dangerous strain resistant to many antibiotics

• Penicillin resistance developed in 1945

• methicillin resistance developed in 1961

• How it works:

  • Methicillin blocks a protein needed to build bacterial cell walls. MRSA uses a diffrent protien

• Natural selection:

  • MRSA survives and reproduces when exposed to methicillin, while non-resistant bacteria are more likely to die

Homology

Similarity resulting from common ancestry

Homologous Structures

Anatomical resemblances representing variations on a structural theme present in a common ancestor

• ex: batwing, human forelimb, horse leg are all examples

Vestigial Structures

What’s left of features that served significant functions for an organism’s ancestors

• ex: Genes

Evolutionary Trees

Hypothesis about relationships among different groups

Convergent Evoloution

Evolution of similar, or analogous features in distinctly related groups.

• Doesn’t provide information about ancestry

Why do analogous traits arise?

They arise when groups independently adapt to similar environments in similar ways.

Biogeography

Study of geographic distribution of species, providing evidence of evoution

What was the single continent, but was separated by a continental drift?

Pangaea

Relative Fitness

The contribution an individual makes to the gene pool of the next generation, relative to the contributions of other individuals

What are the three modes of selection?

Directional, Disruptive, and Stabilizing

Directional Selection

Favors individuals at one end of the phenotypic range

Disruptive Selection

Favors individule’s at both extremes at the phenotypic range

Stabilizing Selection

Favors intermediate variants and acts against extreme phenotypes