Grade 10 Biology notes(cells,cancer,diff systems in the body)

1. The Cell

A cell is the basic unit of life. All living organisms are made of cells.

Cells:

  • carry out life processes

  • contain genetic information (DNA)

  • can reproduce by dividing

Cells are surrounded by a cell membrane that separates the inside of the cell from the environment.

Cells contain biological molecules such as:

  • DNA

  • proteins

  • sugars

  • lipids

Cell Theory (Memorize exactly)

  1. All living things are made of one or more cells.

  2. The cell is the basic unit of structure and function in living things.

  3. All cells arise from pre-existing cells.

These principles explain how organisms grow, repair themselves, and reproduce.

Types of Cells

Prokaryotic Cells

Characteristics:

  • simple structure

  • no nucleus

  • no membrane-bound organelles

  • DNA floats freely in cytoplasm

Examples:

  • bacteria

They are usually smaller and simpler than eukaryotic cells.

Eukaryotic Cells

Characteristics:

  • complex structure

  • have a nucleus

  • contain membrane-bound organelles

Examples:

  • plant cells

  • animal cells

  • fungi cells

Humans are made of eukaryotic cells.

Specialized Cells

Specialized cells are cells that have specific structures adapted for a particular function.

Examples:

Red Blood Cells

Function:

  • transport oxygen throughout the body

Special features:

  • contain hemoglobin

  • flexible shape

  • no nucleus (in humans)

Nerve Cells (Neurons)

Function:

  • transmit electrical signals between the brain and body

Structure:

  • long extensions called axons

Muscle Cells

Function:

  • contract to produce movement

Sperm Cells

Function:

  • deliver male genetic material to egg

Features:

  • flagellum (tail) for movement

Egg Cells

Function:

  • female reproductive cell

  • provides nutrients for early development

Organelles

Organelles are specialized structures within cells that perform specific functions.

Cell Membrane

Function:

  • controls what enters and leaves the cell

  • protects the cell

Properties:

  • semi-permeable (selectively permeable)

Allows:

  • oxygen

  • nutrients

  • water

to enter.

Allows wastes to leave.

Transport processes include:

  • diffusion

  • osmosis

Cytoplasm

Description:

  • jelly-like fluid inside the cell

Functions:

  • holds organelles in place

  • site of many chemical reactions

  • allows movement of materials inside the cell

Cytoskeleton

Structure:

  • network of protein fibers

Functions:

  • maintains cell shape

  • helps move organelles

  • helps cell movement

Nucleus

Function:

  • control center of the cell

Contains:

  • DNA (genetic instructions)

Other roles:

  • controls cell growth

  • controls protein production

  • regulates cell division

Usually the largest organelle.

Nucleolus

Found inside nucleus.

Function:

  • produces ribosomes

Ribosomes

Function:

  • synthesize (produce) proteins

Location:

  • free in cytoplasm

  • attached to rough ER

Endoplasmic Reticulum (ER)

Network of membranes that transport materials inside the cell.

Rough ER

  • covered with ribosomes

  • produces proteins

Smooth ER

  • produces lipids

  • detoxifies harmful substances

Golgi Apparatus

Structure:

  • stack of flattened membranes

Function:

  • modifies proteins

  • packages proteins

  • transports proteins to other parts of the cell

Acts like the cell’s shipping center.

Mitochondria

Function:

  • produces energy (ATP)

Process:

  • cellular respiration

Breaks down sugar molecules to release energy.

Structure:

  • outer membrane

  • inner membrane folded into cristae

Lysosomes

Function:

  • digestion of materials

Break down:

  • food molecules

  • waste

  • old organelles

  • foreign materials

Contain digestive enzymes.

Vacuoles

Fluid-filled sacs.

Functions:

  • storage of water

  • storage of nutrients

  • storage of waste

Plant cells usually have one large central vacuole.

Chloroplasts (Plant Cells Only)

Function:

  • photosynthesis

Contain pigment chlorophyll.

Photosynthesis uses sunlight to produce food.

Equation:

CO₂ + H₂O + sunlight → glucose + oxygen

Cell Wall

Found in:

  • plants

  • fungi

  • algae

  • bacteria

Function:

  • provides support

  • protects the cell

  • maintains shape

Made mostly of cellulose in plants.

Comparison of Plant and Animal Cells

Plant Cells:

  • cell wall

  • chloroplasts

  • one large vacuole

  • regular shape

  • no centrioles

Animal Cells:

  • no cell wall

  • no chloroplasts

  • many small vacuoles

  • irregular shape

  • contain centrioles

DNA and Chromosomes

DNA:

  • contains genetic instructions for all cell activities.

DNA is organized into chromosomes.

Humans have:

  • 46 chromosomes total

  • 23 from mother

  • 23 from father

A pair of chromosomes from each parent forms homologous pairs.

Cell Division

Cell division is the process by which a cell divides to form two daughter cells.

Functions of cell division:

  • growth

  • repair of tissues

  • replacement of damaged cells

  • reproduction

Before division:

  • DNA must replicate (copy itself).

The Cell Cycle

The cell cycle consists of stages a cell goes through while growing and dividing.

Stages:

  1. Interphase

  2. Mitosis

  3. Cytokinesis

Interphase

Preparation stage before mitosis.

Three parts:

G1 Phase

  • cell grows

  • organelles increase

S Phase

  • DNA replicates

G2 Phase

  • further growth

  • preparation for mitosis

Mitosis

Mitosis is the division of the nucleus.

Produces two identical daughter cells.

Stages:

PMAT

Prophase

Events:

  • chromosomes condense

  • nuclear membrane dissolves

  • spindle fibers form

  • centrioles move to opposite poles

Metaphase

Events:

  • chromosomes line up at the metaphase plate

  • spindle fibers attach to centromeres

Anaphase

Events:

  • sister chromatids separate

  • chromatids move to opposite poles

Each chromatid becomes an individual chromosome.

Telophase

Events:

  • chromosomes reach poles

  • nuclear membranes reform

  • chromosomes return to chromatin form

  • spindle fibers disappear

Cytokinesis

Division of the cytoplasm.

Results in two separate daughter cells.

In Animal Cells

Process:

  • cleavage furrow forms

  • cell membrane pinches inward

In Plant Cells

Process:

  • cell plate forms

  • vesicles fuse to form new cell wall

Reproduction

Asexual Reproduction

Characteristics:

  • one parent

  • identical offspring

  • no genetic variation

Example:

  • bacteria dividing

Process uses mitosis.

Sexual Reproduction

Characteristics:

  • two parents

  • genetically unique offspring

  • involves meiosis

Produces gametes (sex cells):

  • sperm

  • egg

Cancer

Cancer is a group of diseases caused by uncontrolled cell division.

Normally:

  • cell cycle is controlled by checkpoints.

Cancer occurs when mutations in DNA disrupt these controls.

Causes of Cancer

Genetic Factors

Inherited mutations.

Environmental Factors

  • chemicals

  • pollution

  • toxins

Radiation

  • UV radiation

  • X-rays

Viruses

Some viruses can damage DNA.

Lifestyle Factors

  • smoking

  • poor diet

  • lack of exercise

Tumors

Uncontrolled cell growth forms a tumor.

Benign Tumor

  • non-cancerous

  • does not spread

Malignant Tumor

  • cancerous

  • spreads to other tissues

Metastasis

Process where cancer spreads to other parts of the body through:

  • blood

  • lymph system

Tissues

A tissue is a group of similar cells that perform a specific function.

Four major types:

Epithelial Tissue

Functions:

  • protection

  • absorption

  • secretion

Found in:

  • skin

  • lining of digestive tract

  • lining of organs

Cells are tightly packed.

Muscle Tissue

Function:

  • movement

Three types:

Skeletal Muscle

  • voluntary movement

  • attached to bones

Smooth Muscle

  • involuntary movement

  • found in organs

Cardiac Muscle

  • found in heart

  • pumps blood

Nervous Tissue

Function:

  • transmit electrical signals

Found in:

  • brain

  • spinal cord

  • nerves

Allows body to respond to stimuli.

Connective Tissue

Functions:

  • support

  • connect structures

  • transport substances

Examples:

  • bone

  • blood

  • cartilage

  • ligaments

  • tendons

Levels of Organization

Biological organization:

Cell
→ Tissue
→ Organ
→ Organ System
→ Organism

Example:

muscle cell → muscle tissue → heart → circulatory system → human

Body Systems

Digestive System

Function:

  • break down food into nutrients

Main organs and roles:

Mouth

  • mechanical digestion (chewing)

  • saliva begins chemical digestion

Esophagus

  • moves food to stomach

Stomach

  • acids and enzymes break food down

Small Intestine

  • digestion continues

  • nutrients absorbed into blood

Large Intestine

  • absorbs water

  • forms feces

Liver

  • produces bile for fat digestion

Pancreas

  • produces digestive enzymes

Circulatory System

Function:

  • transport oxygen, nutrients, hormones, waste

Main components:

Heart

pumps blood

Blood Vessels

Arteries:

  • carry blood away from heart

Veins:

  • carry blood to heart

Capillaries:

  • allow exchange of substances

Blood

Red blood cells → oxygen transport
White blood cells → immune defense
Platelets → blood clotting

Respiratory System

Function:

  • gas exchange

Organs:

Nose

filters air

Trachea

air passage

Bronchi

branches into lungs

Lungs

gas exchange occurs

Alveoli

tiny air sacs where oxygen enters blood and CO₂ leaves