Biology and Society

unit one

Eukaryotic cell

• Lipid bilayer membrane enclosed internal compartments (fat layer) 

• Membrane bound  

• Larger and more complex  

• Evolved from prokaryotic cells  

• Uni or multicellular  

Prokaryotic cell

• Simplest and most basic cell 

• Don't have a nucleus 

• Before nucleus  

• No membrane bound organelles 

• Nucleoid and nucleus are not the same thing because the nucleoid is not membrane bound  

• Oldest type of cell  

• Single celled  

• Single circular chromosome  

Similarities between both eukaryotic cells and prokaryotic cells  

• Both have DNA  

• Have ribosomes  

• Have cytoplasm  

• Cell membrane  

• Both produce energy  

Plant cell

• Cell wall  

• Large central vacuole (stores water) 

• Chloroplast  

• Lack centrosomes  

• Lack lysosomes  

animal cell

• No cell wall  

• Numerous small vacuoles  

• No chloroplasts  

• Centrioles/ centrosomes  

• Lysosomes

Hydrophobic  

• Scared of water  

• Lipids do not interact well with water  

Four main components of a cells: 

• Plasma membrane 

• DNA 

• Cytoplasm (semifluid matrix of cellular substructures and cytosol) 

• Ribosomes (synthesize proteins)  

The Nucleus

• The control center of the eukaryotic cell  

• Enclosed by the double membrane nuclear envelope  

• Has nuclear pores that allow chemical messages in and out  

Endoplasmic Reticulum

• Interconnected network of sacs made of a singular membrane continuous with the nuclear envelope  

• Makes and modifies different substances for the cell  

Golgi Apparatus

Packages proteins and lipids into vesicles and directs them to their final destination inside or outside of the cell  

Lysosomes

• The garbage and recycling centers of the cell 

• Contain enzymes that break down large biomolecules  

• Not found in plants or fungi  

Vacuoles

• Multiple functions include  

• Water balance and storage  

• Toxic waste storage  

Mitochondria

• Powerhouse of the cell  

• Transforms the energy of food molecules into ATP cellular fuel in a process called cellular respiration  

• Surrounded by a double membrane  

Chloroplast

• Double membrane bound  

• Capture energy from sunlight and use to make sugar molecules via photosynthesis 

• Found only in cells of plants and some protists

cytoskelton

• A network of protein cylinders and filaments that forms the framework of a cell  

• Supports the movement of organelles  

• Can enable whole cell movement  

• Gives shape to cells without cell walls  

• Little highways inside cells  

Cell theory

1. All organisms are composed of one or more cells  

2. All cells. Arise from pre-existing cells 

3. The cell is the structural and functional unit of all living things 

what is life

• Cells  

• Needs DNA/Hereditary information  

• Needs energy  

• Can reproduce  

• Evolves  

• Maintain a constant internal environment  

• Evolve as groups 

• Obtain energy from the environment to support metabolism  

• They sense the environment and respond to it

Cells

• Smallest unit of life  

• Microscopic self-contained unites enclosed by a protective membrane  

• The human body is composed of 100 trillion (1014) cells  

Prokaryotes

• Pro=before  

• Karyo= nucleus  

• Bacteria and archaea  

• Cytoplasm 

• DNA the genetic material  

• Ribosomes: molecular machines that produce protein  

• No nucleus or membrane bound organelles  

Eukaryotes

• Eu= true  

• Karyo= nucleus  

• Protists, Fungi, Animals, Plants  

• May be single celled or multicellular  

• Their DNA is enclosed in a double membrane enclosed nucleus  

• Contain a variety of membrane enclosed compartments called organelles  

• Lipid bilayer membrane enclosed internal compartments  

• They concentrate and organize cellular chemical reactions  

• Their volume can be a thousand times larger than prokaryotic cells  

Bacteria and Archaea cells

• A protective cell wall surrounds the plasma membrane  

• Some have a capsule around the cell wall  

• Helps disease-causing bacteria evade the immune system

• Some have short hairlike pili 

• To link together  

• To attach to surfaces 

• Some have long whiplike flagella  

Archaea

• The domain Archaea is well known for the extreme lifestyles of its members 

• Thermophiles love the heat 

• Halophiles love salt  

Science

a body of knowledge (data) about the natural world

• An evidence-based process

• Must be detectable, observable, and measurable

• Based on evidence that can be demonstrated through

observations and/or experiments

Scientific Method

The scientific method, or the process of science, are the practices that produce scientific knowledge

Observation

a description, measurement, or record of any object or phenomenon.

Hypothesis

is an informed, logical, and plausible explanation for observations of the natural world.

▪ A hypothesis must be

• Testable

• Falsifiable

― It must make predictions that can be clearly determined to

be true or false.

• Is not an “if . . . then” statement

Observational study

Descriptive: reporting data found in nature

• Analytical: measurements that

can then be analyzed with statistics

Experiment

is a repeatable manipulation of one or more aspects of the natural world.

Independent variable

manipulated by scientists

Dependent Variable

responds to changes in the independent variable – what the scientist measures

Experimental study

a controlled scientific investigation used to test a hypothesis and discover cause-and-effect relationships in living systems

Control Group

Group that gets no treatment

Used for comparison

Treatment Group

The experimental group(s)

Same set of conditions as the control group, except the

independent variable is manipulated

Peer Review

are found in scientific journals

• has passed scrutiny of experts who have no direct involvement in the research under review

• main mechanism for policing personal or group bias and fraud in science

Primary Literature

first publication of scientific research that contains actual data with controls

• Peer-reviewed science journals and dissertations

Secondary Literature

gives a basic overview of a topic or summarizes an area of research

• Textbooks, review articles, popular science magazines, reputable news outlets, or respected institutions

Scientific Theory

Is a broad explanation for a wide range of phenomena

• Has such a high level of certainty that no new evidence is likely to refute it

• Examples: Cell Theory, Germ Theory

Scientific Fact

is a direct and repeatable observation of the natural world.

Abstract

A standard abstract covers five essential parts of the research:

• Purpose: The main objective, research question, or problem the study addresses.

• Context: Brief background information showing what is already known.

• Methods: The research design, data collection tools, and analysis procedures.

• Results: The primary findings or outcomes.

• Conclusion: The main takeaway and broader implications of the work

Introduction

An introduction in a research paper is the opening section that sets up your topic, provides background context, and explains why your specific study is necessary. It typically forms about 10% to 15% of the total paper length

materials and methods

a comprehensive description of what physical and informational resources were used and how the study was conducted

Results

the recorded data, observations, and measurements gathered during an experiment or study

Discussion

the specific section of a lab report, research paper, or scientific manuscript where the author interprets and evaluates the meaningful biological significance of their experimental results

Scientific Literacy

an understanding of the basics of science and the scientific process.

• Enables us to use critical thinking to make informed decisions

• Enables us to communicate our knowledge to others

Scientific Claims

a statement about how the natural world works that can be tested using the scientific method

Pseudoscience

is characterized by scientific-sounding statements,beliefs, or practices that are not based on the scientific method.

Bias

a prejudice or opinion for or against something

Credentials

the qualifications to be recognized as an authority on the subject.

• Do they have an advanced degree, such as a PhD or MD?

• Is their degree in the field related to their claims?

Correlation

means that two or more aspects of the natural world behave in an interrelated manner.

• If one aspect shows a particular value, we can predict a value for the other aspect.

• But, the first aspect may or may NOT be the cause of the other aspect.

Causation

a change in one biological factor directly produces a change or specific outcome in another

meta-analysis

a research paper that combines results from different studies suggests that physicians should:

• strongly recommend the vaccine to parents.

• alleviate HPV vaccine safety concerns.

• promote trust in vaccines.

Anecdote

an isolated, uncontrolled observation or a personal report about a single biological event, patient case, or animal behavior.

Basic research

scientific experimentation aimed at expanding fundamental knowledge about living systems and cellular processes without an immediate practical goal

Applied Research

uses existing scientific knowledge to solve specific, practical problems affecting living organisms, human health, agriculture, or the environment

Clinical Trial

Effectiveness of intervention to treat a disease

• Safety of a new drug

• Defining dose administration

• Testing drug formulation

• Exploring combination therapies

• Evaluating effect of therapies on quality of life

Informed Consent

Learning the key facts about a trial before deciding whether to participate

• Research study purpose

• Risks/Benefits

• Alternative treatments

• Confidentiality of records

• Medical treatment available if injury occurs

• Whom to contact for answers to questions

• Statement that participation is voluntary

• This is mandatory for a clinical research trial

Institutional Review Board

All clinical trials must be approved and monitored by an IRB. IRB is an independent committee of physicians, nurses, statisticians, community advocates and others. The function of the IRB is to ensure that a clinical trial is ethical and the rights welfare of study participants are protected.

Belmont Report

a foundational document outlining ethical principles for human subjects’ research, published in 1979 by the U.S. National Commission for the Protection of Human Subjects.

Placebo Effect

a real physical or chemical change in the body caused by a person's expectation of healing rather than an active medicine

Adverse Events

an undesired, harmful, or damaging change that happens to an organism or biological system after exposure to a chemical, drug, or other intervention

Phase 1

15 to 30 participants, first in humans, find safety

Phase 2

less than 100 participants determine efficiency

Phase 3

100 to 1000 participants, compare new agent with standard treatment

Phase 4

several hundreds to several thousands of participants, post market, long term safety and efficacy

Randomized Control Trial

a scientific experiment where study subjects are assigned by chance to either an experimental group receiving a specific intervention or a control group receiving a placebo or standard care

Double blind study

an experimental design in biology and clinical research where neither the participants nor the researchers know who is receiving the active treatment and who is receiving a placebo or contro

Placebo controlled study

a scientific test where researchers compare a new medical treatment against an inactive dummy treatment, called a placebo, to see if the real treatment actually works

Efficiency

how well an organism, cell, or ecosystem uses energy and resources to grow, survive, and reproduce with the least amount of waste

Exclusion criteria

the specific characteristics, conditions, or factors that disqualify a prospective participant, animal model, or sample from being included in a study

Inclusion Criteria

the mandatory traits or standards that a subject, sample, or data point must possess to be part of a study

Pre clinical Trial

a phase of research that tests a new drug, medical device, or treatment in and/or animal models] before any testing is allowed in humans

Respect

"respect" does not have a formal definition, as it is a human social and philosophical concept rather than a biological process or structure

Cell

the smallest unit of life

• Microscopic, self-contained units enclosed by a protective membrane

 The human body is composed

of ~100 trillion (1014) cells

Carbohydrates

Sugars and starches

•The Job: Your body’s preferred source of immediate energy.

•The Structure: Usually shaped like rings or long chains of rings.

Lipids

Fats, oils, and waxes

•The Job: Long-term energy storage and creating plasma and organelle membranes of every cell.

•The Structure: Long, hydrophobic (water-fearing) tails that don't mix with water.

Proteins

Complex chains made of amino acids

•The Job: They do almost everything! They build muscle, move oxygen in your blood, and act as enzymes

(the catalysts that speed up chemical reactions).

•The Structure: Highly complex 3D shapes. If a protein loses its shape, it stops working.

Nucleic Acids

DNA and RNA

•The Job: Storing and transmitting genetic information.

•The Structure: A double helix (for DNA) made of a sugar-phosphate backbone and nitrogen "bases."

Phospholipids

The Cell Builders

• Structure: Composed of one glycerol "head," a

phosphate group, and only two fatty acid tails.

Metabolism

the sum of all chemical reactions that happen inside a living organism to sustain life

Homeostasis

the self-regulating process by which a biological system maintains a stable, balanced internal environment despite changes in the outside world

Organelle

a tiny, specialized structure inside a cell that performs a specific job, much like an organ does in the whole body

DNA

the molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all living organisms

ATP

the primary molecule that living cells use to store, transfer, and spend energy

Cellular Respiration

the metabolic process cells use to convert nutrients like glucose into usable energy in the form of ATP (adenosine triphosphate), releasing carbon dioxide and water as waste

Sugar

a generic term for short-chain, soluble carbohydrates made of carbon, hydrogen, and oxygen that serve as a primary source of cellular energy and structural components

Photosynthesis

the biological process by which green plants, algae, and certain bacteria convert light energy into chemical energy

Phospholipid Bylayer

a double layer of lipid molecules that forms the fundamental barrier of all cell membranes and organelle boundaries

Selective Permeability

a barrier that allows certain molecules or ions to pass through while blocking others

The 6 characteristics of life

They are composed of one or more cells.

2. They reproduce autonomously using DNA.

3. They obtain energy from the environment to support metabolism.

4. They sense the environment and respond to it.

5. They maintain a constant internal environment.

6. They can evolve as groups

4 main concepts of a cell

Plasma Membrane

2. DNA

3. Cytoplasm

• Semifluid matrix of cellular substructures and cytosol

4. Ribosomes

• Synthesize proteins

Tree of Life

a graphical representation of all known species arranged as a branching tree

• shows evolutionary relationships among the species (DNA similarity)

3 domains of life

Eubacteria (bacteria)

2. Archaea

3. Eukarya

4 kingdoms

Plantae

2. Protists

3. Animalia

4. Fungi

Binary Fission

a type of asexual reproduction where a single parent cell divides into two genetically identical daughter cells

Capsule

a thick, protective outer layer of gelatinous material—usually made of polysaccharides—that surrounds the cell wall of some bacteria and fungi

Pili

thin, hair-like protein tubes found on the surface of many bacteria

Flagella

microscopic, hair-like cellular appendages primarily responsible for cell locomotion

Extremophile

an organism that grows, survives, and thrives in physical or geochemical conditions

Quorum Sensing

a process of cell-to-cell communication that allows bacteria to track their population density and change their behavior together when a threshold number is reached.

Biofilm

a structured community of microorganisms—such as bacteria, fungi, or algae—stuck to a surface and enclosed in a self-produced sticky slime matrix