Cell Structures & Organelles

Unit 2

What does cells mean?

Cells are the basic structural and functional units of all living organisms, serving as the building blocks of life.

What does unicellular mean?

Unicellular refers to organisms that consist of a single cell.

Provide Unicelluar examples

bacteria

What does Multicelluar mean

Oraganism made of many cells

Provide a multicellular example (3)

plants, animals, fungi

Define prokaryotic cell

A cell lacking a nucleus and membrane-bound organelles.

Provide a prokaryotic example

Bacteria

Define Eukaryotic cells

A type of cell that has a nucleus and membrane-bound organelles

Provide examples for Eukaryotic cells (4)

Examples include animals, plants, fungi, and protists.

Define Membrane-Bound Organells

Structures inside a cell that are surrouned by their own membrane and perform specific jobs

Provide examples for Membrane-Bound Organells

Chlorplast,Golgi Apparatus, endoplasmic reticulum (or ER), lysosomes.

Define Specialized cells

A cell with unique structures or features that help it perform a specific job

Examples for specialized cells

muscle cells, nurons

Def. Tissue

A group of similar cells working together to perform a specific function

Examples for tissue

muscle tissue,

Who coined the term “cells”

robert Hooke in 1665

What did Robert Hook look at through his microscope?

dead cork

Who coined the term animalcules?

Antwon Van Leeuwenhoek

Who concluded all plants are made of cells?

Mattias Schleiden

Who concluded all animals are made of cells?

Theodor Schwann

WHo concluded new cells come from pre-existing cells?

Rudolf Virchow

What are the 3 components of cell theory?

All living animals are made of one or more cells.
The cell is the basic structure for all oreganisms
New cells are created by the division of pre-existing cells

Do Prokaryotic cells have a nucleus?

No

Do Prokaryotic cells have membrane bound organells?

No

Prokarytic cells can be uni or multi cellular (T/F)

F

Prokaryotic DNA structure/shape

circluar

Prokaryotic cell examples….(2)

Bacteria and Archaea

Do Eukaryotic cells have a nucleus?

Yes

Do Eukaryotic cells have circular DNA

No, they have linear DNA.

Eukaryoic cells can only be multi cellular (t/f)

f

Eukarotic examples (4)

Animals, plants, fungi, protists

Pro/Euk:

A microscopic organism is found in a hot spring. The cell contains a single loop of DNA floating freely in the cytoplasm. There are no visible internal compartments or membrane bound structures.

Pro

Pro/Euk

A cell is isolated from a leaf sample. It features a distinct, membrane bound nucleus and several large green chlroplasts. The DNA is organizes into linear chromosomes

Euk

Pro/Euk:

A single-celled organism isolated from pond water contains a distinct nucleus, linear chromosomes, and membrane-bound mitochondria.

Euk

Pro/Euk:

A newly discovered bacterium from a soil sample contains ribosomes and a cell wall, but lacks a membrane-bound nucleus and has a single circular chromosome.

Pro

Four cellular structures shared by all three cell types: bacterial, animal, and plant

Cell membrane, cytoplasm, ribosomes, and DNA

Structures present in plant cells that are absent in animal cells

Cell wall, chloroplasts, and a large central vacuole

Structure found in animal cells used during cell division that is absent in plant and bacterial cells

Centrioles

Which of the three cell types possess a rigid cell wall?

Bacterial cells and plant cells (animal cells lack a cell wall)

Key difference between bacterial cells and plant/animal cells regarding cell organization

Bacterial cells are prokaryotic and lack a nucleus or membrane-bound organelles, while plant and animal cells are eukaryotic and possess a membrane-bound nucleus and organelles.

Membrane-bound organelles present in both plant and animal cells, but absent in bacterial cells

Nucleus, nucleolus, mitochondria, endoplasmic reticulum (rough and smooth), and Golgi apparatus

Protein-making structures found in all three cell types (bacterial, animal, and plant)

Ribosomes

True or False: Animal cells have a cell wall and chloroplasts.

False (animal cells lack both a cell wall and chloroplasts)

Cell Membrane

The selective boundary of the cell that acts as a barrier, regulates what enters and leaves (such as nutrients, water, and waste), helps maintain a stable internal environment, and contains proteins for external cell communication. Found in bacterial, animal, and plant cells.

Cytoplasm

The gel-like fluid inside the cell that provides structural support, prevents the cell membrane from collapsing, holds organelles in position, hosts chemical reactions, transports molecules, and stores chemicals like water, salts, sugars, and amino acids. Found in bacterial, animal, and plant cells.

Ribosomes

Tiny structures made of two parts (subunits) that read instructions from DNA to assemble proteins; they can float freely in the cytoplasm or attach to the rough ER. Found in bacterial, animal, and plant cells.

Nucleus

The control center of the cell that contains genetic material (DNA) and directs cell activities such as growth, reproduction, and protein synthesis. Found in animal and plant cells.

Nuclear Envelope

A double membrane that encloses the nucleus and separates the DNA from the rest of the cell.

Mitochondria

The cell's energy producers that break down food molecules through cellular respiration to produce a usable form of energy ($\text{ATP}$) to support growth, movement, and material transport. Found in animal and plant cells.

Cristae

The folds of the inner mitochondrial membrane that provide an increased surface area for the chemical reactions of cellular respiration to occur.

Rough Endoplasmic Reticulum (Rough ER)

A protein processing and transport system studded with ribosomes that helps fold and modify newly synthesized proteins before moving them across the cell or packaging them into vesicles for the Golgi apparatus. Found in animal and plant cells.

Smooth Endoplasmic Reticulum (Smooth ER)

A membrane network that synthesizes lipids (fats, phospholipids, and steroid hormones), detoxifies drugs and poisons, stores calcium ions (in cells like muscle cells), and participates in metabolism. Found in animal and plant cells.

Golgi Apparatus

The cell's packaging and shipping center that makes final modifications to proteins and lipids received from the endoplasmic reticulum, sorts them into vesicles, and directs them to other organelles or secretes them from the cell. Found in animal and plant cells.

Centrioles

Cylindrical structures made of tubulin (microtubules) positioned in pairs at right angles that organize the cytoskeleton and form spindle fibers to separate chromosomes during cell division. Found only in animal cells.

Lysosomes

Digestive organelles containing enzymes that break down old cell parts, waste products, and foreign invaders (such as bacteria or viruses), recycling the component building blocks for the cell to reuse. Found in animal cells.

Vesicles / Vacuoles

Small, membrane-bound sacs that store substances (water, nutrients, waste) and transport molecules (proteins and lipids) between organelles, to the cell membrane, or outside the cell. Found in animal and plant cells.

Chloroplasts

Organelles that capture solar light energy to produce glucose for the plant during photosynthesis; they contain the light-absorbing pigment chlorophyll. Found only in plant cells.

Large Central Vacuole

A large plant organelle that stores water, nutrients, and waste materials; by maintaining turgor pressure, it keeps the plant cell rigid and upright. Found only in plant cells.

Cell Wall

A rigid outer protective layer that gives structure, shape, and strength to the cell, preventing plant cells from bursting when water enters and protecting bacterial cells from their environment. Found in bacterial and plant cells.

Cytoskeleton

An internal framework of fibers that maintains cell shape, organizes organelles, facilitates cell and organelle movement (including cilia and flagella), and forms spindle fibers to separate chromosomes during division. Found in bacterial, animal, and plant cells.

Pili

Hair-like appendages on bacterial cells that allow them to stick to surfaces or host tissues, assist in building biofilm communities, or transfer genetic material via specialized sex pili. Found only in bacterial cells.

Flagellum

A long, whip-like appendage that spins or waves to enable cell locomotion toward nutrients, favorable environments, or hosts. Found in many bacterial cells and specialized animal cells (such as sperm cells).

DNA

The hereditary material containing the genetic instructions required to synthesize proteins and direct cellular functions; located in the nucleoid region of bacteria and inside the nucleus of animal and plant cells. Found in bacterial, animal, and plant cells.

Cell membrane

Controls what enters and leaves the cell.

Cytoplasm

Gel-like material that supports cell structures and is where many reactions occur.

Ribosomes

Makes proteins.

DNA

Contains the genetic instructions for the cell.

Cytoskeleton

Provides shape, support, and helps with movement within the cell.

Nucleus

Contains and protects the cell's genetic instructions (DNA).

Nucleolus

Makes ribosomes.

Mitochondria

Releases usable energy from food (cellular respiration).

Rough endoplasmic reticulum (rough ER)

Helps make and transport proteins (has ribosomes).

Smooth endoplasmic reticulum (smooth ER)

Makes lipids (fats) and helps break down/detoxify harmful substances.

Golgi apparatus

Modifies, sorts, and packages proteins for transport.

Lysosomes

Breaks down waste materials, worn-out organelles, and harmful substances.

Vacuoles

Stores water, food, and other materials.

Chloroplasts

Captures sunlight to make food (photosynthesis).

Cell wall

Provides rigid support and protection.