Prokaryotes vs. Eukaryotes

• All living organisms consist of one or more cells
• The cell is the fundamental unit of life
• All cells originate from pre-existing cells

Prokaryotes vs. Eukaryotes

• Prokaryotes do not have a nucleus; their DNA floats freely in the cytoplasm
• Eukaryotes possess a nucleus which contains DNA
• Membrane-bound organelles are absent in prokaryotes
• Membrane-bound organelles are present in eukaryotes, examples include mitochondria, endoplasmic reticulum (ER) and the Golgi apparatus
• Prokaryotes are smaller, ranging from 1–10 µm
• Eukaryotes are larger, ranging from 10–100 µm
• Prokaryotes exhibit a simple structure
• Eukaryotes exhibit a complex structure
• Prokaryotic DNA is circular and single-stranded
• Eukaryotic DNA is linear, double-stranded, and arranged in chromosomes
• Prokaryotes reproduce asexually through binary fission
• Eukaryotes reproduce sexually via meiosis or asexually through mitosis
• Examples of prokaryotes are bacteria and archaea
• Examples of eukaryotes are animals, plants, fungi, and protists

Cell Cycle Key Terms

• Interphase involves growth and DNA replication
• Mitosis is the DNA division phase
• Cytokinesis is the final separation stage

Organelles

• Mitochondria make energy (ATP) in the cytoplasm; they are the "power plant"
• The Nucleus stores DNA and controls the cell; it's the "control center"
• Chloroplasts(plants only) facilitate photosynthesis and are the "solar panel"
• Cell Walls (plants only) provide structure and support

Animal vs Plant Cells

• Animal cells lack a cell wall whereas plant cells have a cell wall for structure and support
• Animal cells lack chloroplasts
• Plant cells have chloroplasts for photosynthesis
• Animal cells have small and multiple vacuoles if they are present
• Plant cells have one large central vacuole that stores water and nutrients
• Animal cells have a round or irregular shape
• Plant cells have a rectangular, fixed shape due to the cell wall
• Animal cells produce energy using only mitochondria
• Plant cells use both mitochondria and chloroplasts for energy, with chloroplasts enabling them to make their own food
• Animal cells divide with a cleavage furrow forming during cytokinesis
• Plant cells form a cell plate during cytokinesis

Interphase

• Interphase is the combined phases of G1, S, and G2 of the cell cycle.

Interphase - G1 Phase (Gap 1)

• G1 Phase is the first growth phase
• The purpose of G1 Phase is for cell growth in size, performing normal functions and producing proteins and organelles
• During the G1 Phase checkpoint, the cell checks for DNA damage and readies itself for DNA replication.

Interphase - S Phase (Synthesis)

• S Phase is the DNA synthesis phase
• During S Phase, the cell replicates its DNA, giving each new cell a complete set of genetic instructions.
• Each chromosome duplicates, and two sister chromatids are formed, connected by a centromere.

Interphase - G2 Phase (Gap 2)

• G2 Phase is the second growth phase.
• The cell continues to grow, makes final preparations for division, and produces organelles needed for mitosis.
• During G2 Checkpoint the cell ensures the DNA replication was successful and repairs any errors.

Key Terms

• Cell Division is the formation of two identical daughter cells from a single parent cell
• A Centriole is a cylindrical organelle in animal cells that is involved in cell division
• Centrioles form spindle fibers, which separate chromosomes during cell division
• The Centromere is the part of a chromosome where the chromatids are attached
• During mitosis, spindle fibers attach to the chromosome at the centromere
• A Chromatid is one of two identical halves of a replicated chromosome
• Chromatin refers to DNA strands in the nucleus during interphase
• Chromatin stains dark
• The term "chroma" means color in Greek
• A Chromosome is a structure formed from condensed chromatin
• Chromosomes consist of two identical chromatids attached at the centromere, giving them an "X" shape
• Chromosomes occur in pairs; human cells contain 23 pairs/46 total chromosomes
• An organism gets half of it's chromosomes from each parent
• Cytokinesis is the division of the cell's cytoplasm to form two daughter cells
• DNA/deoxyribonucleic acid is a molecule that carries genetic information
• Interphase is when the cell grows, matures, and duplicates genetic information
• Mitosis is the equal division of chromosomes into two genetically identical daughter nuclei
• Four stages in Mitosis are: Prophase, Metaphase, Anaphase and Telophase

Mitosis Phases

• Mitosis is a form of cell division that produces two identical daughter cells with the same chromosome number as the original cell.
• Mitosis is need for growth, repair and maintenance

Mitosis - Prophase

• Chromatin condenses into visible chromosomes
• DNA coils tightly, forming thick, X-shaped chromosomes
• Each chromosome has two identical sister chromatids joined at a centromere
• The nuclear membrane and nucleolus disappear
• Freed chromosomes can move around
• Centrioles move to opposite poles of the cell
• Spindle fibers (microtubules) form and extend from centrioles

Identifying Prophase

• Chromosomes are thick and visible
• No nuclear membrane or nucleolus visible
• Spindle fibers are starting to appear

Mitosis - Metaphase

• Chromosomes align along the cell’s equator, forming the metaphase plate
• Spindle fibers attach to the centromere of each chromosome
• Proper alignment ensures identical chromosomes

Identifying Metaphase

• Chromosomes are lined up in a straight line across the middle
• Spindle fibers attach to centromeres
• Chromosomes are at their most condensed state

Mitosis - Anaphase

• Spindle fibers shorten, pulling the sister chromatids apart
• Each sister chromatid becomes an individual chromosome
• Chromosomes are pulled toward opposite poles
• The cell elongates as the poles separate

Identifying Anaphase

• Chromosomes appear V-shaped as they are pulled apart
• Sister chromatids move away from the middle to opposite sides
• The cell appears stretched

Mitosis - Telophase

• Chromosomes reach opposite poles and decondense back into chromatin
• Nuclear membranes reform around each set of chromosomes
• The nucleolus reappears in each new nucleus
• Spindle fibers disappear.
• The cell contains two nuclei within the same cytoplasm

Identifying Telophase

• Two distinct nuclei are visible
• Chromosomes are less condensed
• The cell membrane begins to pinch inward in animal cells, or a cell plate forms in plant cells

Cytokinesis

• Cytoplasm divides, making two identical daughter cells
• In animal cells the cell membrane pinches inward, forming a cleavage furrow until the cell splits
• In plant cells the cell plate forms in the middle and grows outward, becoming the new cell wall

Identifying Cytokinesis

• Two separate cells are visible
• In animal cells, there is a clear cleavage furrow
• In plant cells, the cell plate is visible

Cancer Cells

• Cancer is the uncontrolled division of cells.
• When mutated, cells multiply uncontrollably, losing function, and waste valuable resources.
• Tumors are masses of abnormal cells

Types of Tumors

• Malignant tumors are cancerous and can metastasize (spread)
• Benign tumors are non-cancerous and do not spread

Cancer Terminology

• A Biopsy is a small tissue sample taken to examine for cancer cells
• Mammograms use X-rays to detect cancerous growth in breast tissue
• Metastasis refers to the spread of cancer cells from the primary tumor
• Apoptosis is programmed cell death
• Carcinogens are cancer-causing agents
• ABCDEs of Melanoma include: Asymmetry, Border, Color, Diameter, Evolution

Causes of Cancer

• Genetics and DNA mutations can cause cancer
• Carcinogens are substances that can cause cancer

Specialized Cells

• Specialized cells efficiently perform specific tasks
• The body is made of Specialized cells

Specialised Cells - Features

• Red Blood Cells (RBCs) features include being: small, round, disk-shaped and lacking nuclei, and they transport oxygen from the lungs to the body tissue and carries CO22 out
• Skin Cells features include them being flat and able to stack, providing a barrier against infections.
• Muscle Cells are long, able to retract and expand with mitochondria, and contract/relax to provide movement
• Photosynthetic Cells contain chloroplasts to capture the sun's energy and perform photosynthesis

Cell Specialization

• Cells specialize with adapted structures for performing specific functions efficiently
• Stem Cells differentiate into many different cells and the daughter cells have same genes bnut different functions
• Totipotent cells differentiate into any cell type
• Multipotent cells differentiate only for specific cells, eg Bone marrow Stem Cells
• The Circulatory System transports blood, nutrients, gases and wastes.
• The Digestive System breaks down food, absorbs nutrients, and eliminates waste
• The Immune System defends the body from invaders and prevents infections and diseases.

Body Hierarchy

• The human body is organized into levels of complexity: Cells, Tissues, Organs, Organ Systems
• A Cell is the basic unit of life and smallest living structure. Each cell type is specialized.
• Tissues are groups of similar cells working together
• Organs are structures made of two or more tissue types; the heart pumps blood
• Organ Systems are groups of organs working together; the digestive system includes organs like the stomach, intestines, and liver
• An Organism (body) is the complete living being from the interaction of all organ systems