Cell Structures

A __ is the structural and functional unit of life

cell

All cells have some common structures and functions.

3 important components of the cell include

1.      Plasma membrane: flexible outer boundary

2.      Cytoplasm: intracellular fluid containing organelles

3.      Nucleus: DNA containing control center

Plasma/Cell Membrane

Acts as an active barrier separating intracellular fluid (ICF) from extracellular fluid

(ECF)

The functions of the plasma membrane

1. Acts as a physical barrier enclosing the cytoplasm from the extracellular space

2. Cell recognition (think glycocalyx and cancer cells)

3. Selective permeability

4. Electrochemical gradient/communication (proteins channels used to communicate and transport)

Plasma Membrane consists of

Lipids

Proteins

Glycocalyx (glyoproteins and glycolipids)

Cholesterol

Glycocalyx

Sugars (Carbohydrates) sticking out of cell surface

Are sugars Carbohydrates?

Yes

Does the Glycocalyx bind to anything in the PM?

Yes the Glycocalyx can bind to proteins and lipids

Glycoprotein

A protein with a carbohydrate (sugar) chain attached to it

Glycolipids

Lipids (fats) with carbohydrate (sugar) chains attached.

How are Glycocalyx’s important

1. Every cell type has different patterns of this “sugar coating”

   1. Functions as specific biological markers for cell- to-cell recognition

   2. Allows immune system to recognize “self” vs. “nonself”

How do cancer cells get around the cell’s ability to recognize non-native cells?

Cancer cells can change the sugar coating on their surface (the glycocalyx) so that the immune system has a harder time recognizing them as abnormal.

Cholesterol

Helps maintain membrane stability

The lipid bylayer of the plasma membrane is made up of

1. Phospholipids (75%)

2. Cholesterol (20%)

3. Glycolipids (5%)

Phospholipids

State the charge and whether it is hydrophobic or hydrophilic

Phosphate Head

2 Fatty Acid Tails

Phosphate heads: are polar (charged), so are hydrophilic (water-loving)

Fatty acid tails: are nonpolar (no charge), so are hydrophobic (water-hating)

True or False

Membrane proteins allow cell communication with environment

True

True or False

Most Integral proteins have specialized membrane functions

True

What are the two types of membrane proteins

1. Integral proteins

2. Peripheral proteins

Integral proteins are they found on the outside of the membrane or are they found through the membrane?

Most are transmembrane proteins (span membrane)

True or False

Integral membrane proteins function as transport proteins (channels and carriers), enzymes, or receptors

True

Peripheral proteins where are they found?

Loosely attached to integral proteins surface of the plasma membrane

True or False

Peripheral proteins function as enzymes, Motor proteins for shape change during cell division and muscle contraction and Cell-to-cell connections

True

What is located between the plasma membrane and the nucleus?

Cytosol: gel-like solution made up of water and soluble molecules such as proteins, salts, sugars, etc.

Inclusions

Organelles: metabolic machinery structures of cell; each with specialized function; either membranous or non-membranous

What are the membranous cytoplasmic organelles?

1. Mitochondria

2. Endoplasmic reticulum

3. Golgi apparatus

4. Peroxisomes

5. Lysosomes

6. Nucleus

What are the non-membranous cytoplasmic organelles?

1. Ribosomes

2. Cytoskeleton

3. Centrioles

Membranous vs Non-Membranous Organelle’s

literally as it sounds, surrounded by membrane vs no membrane

Whats considered the power house of the cell, what organelle produces the most energy (ATP)?

Mitochondria

Does the Mitochondria have a membrane?

Yes, the Mitochondria is enclosed by double membranes

The inner membrane of the Mitochondria has many folds, called __

cristae

What are Cristae and why are they important

Cristae are embedded with membrane proteins that play a role in cellular respiration.

They are important because by helping increase surface area in the inner membrane the cristae help give more room for the proteins involved in cellular respiration which is how the mitochondria makes ATP

Mitochondria contain their own ___, ___, and ____

DNA

RNA

ribosomes

True or False

Mitochondria can use the same type of division as bacterial, called what?

True

Binary Fission

What is the Endoplasmic Reticulum (ER) and where is it found?

A network of membrane-bound tubes and sacs inside the cell

ER is found in cytoplasm around nucleus

Two types of ER

– Rough ER

– Smooth ER

Is the rough ER the internal or external layer of the ER

external layer

The ER is studded with what organelle

Ribosomes

The Rough ER is the sight of what?

1. Site of protein synthesis

2. Site of synthesis of many plasma membrane proteins and phospholipids

The final protein made in rough ER is enclosed in vesicle and sent to what organelle for further processing?

Golgi apparatus

Smooth ER is involved in the synthesis of what?

Lipids (Steroids)

The Smooth ER regulates the concentration of ____ in all cells?

calcium

Which part of the ER is the Sarcoplasmic reticulum found in?

Sarcoplasmic reticulum is specialized smooth ER found in skeletal and cardiac muscle cells

Golgi Apparatus

Modifies and packages the protein (Rough ER) and Lipids (Smooth ER) they recieved from the ER

What are the three steps the Golgi apparatus is involved in

1.    Transport vesicles from ER fuse with cis (inner) face of Golgi

2.    Proteins or lipids taken inside are further modified, sorted, and packaged

3.    Golgi is “traffic director,” controlling which of three pathways final products will take as new transport vesicles pinch off trans (outer) face

Golgi Apparatus

Depending on its contents, final transport vesicles can take one of three pathways:

1. Pathway A: Secretory vesicles containing proteins to be used outside of cell fuse with plasma membrane and exocytosis contents

2. Pathway B: Vesicles containing lipids or transmembrane proteins fuse with plasma membrane or organelle membrane, inserting contents directly into destination membrane

3. Pathway C: Lysosomes containing digestive enzymes remain in cell, holding contents in vesicle until needed

Peroxisomes

detoxifying membranous sacs

True or False

Peroxisomes also play a role in breakdown and synthesis of fatty acids

True

What are Free Radicals and how are they connected to peroxisomes

Free radicals are toxic, highly reactive molecules that are naturally created by cellular respiration. Peroxisomes will destroy these naturally

If Free Radicals aren’t removed they will cause havic

Lysosomes

Membranous sacs containing digestive enzymes (acid hydrolases)

Give exampels of what Lysosomes digest/breakdown

1. bacteria

1. viruses,

2. toxins

3. nonfunctional organelles

If a cell is severely injured or dies, its lysosomal membranes can break down and release these enzymes into the cell. The enzymes can then digest the cell's own components.

What is this process called?

Autolysis

Ribosomes

Non-membranous organelles that are site of protein synthesis

Ribosomes are made up of ___ and ____ ___

protein

ribosomal RNA (rRNA)

Two switchable forms of Ribosomes found in cell:

Free ribosomes

Membrane bound ribosomes

What is the difference between Free Ribosomes and Membrane bound ribosomes

Free = proteins for the cell's interior (cytosol)
Bound = proteins going to the membrane, outside the cell, or through the endomembrane system

Cytoskeleton is an elaborate network of rods that run throughout the ___

cytosol

The cytoskeleton act as the cell’s __, __ and __ by playing a role in movement of cell components

bones, ligaments, and muscle

Three types of Cytoskeletons

What are they?

1. Microfilaments - Thinnest of all cytoskeletal elements

2. Intermediate filaments –      Size is in between microfilaments and microtubules

3. Microtubules - Largest of cytoskeletal elements

What are each of the cytoskeletons parts made of

1. Microfilaments - Actin

2. Intermediate filaments –  Tough, rope like insoluble proteins

3. Microtubules - Hollow tubes of Tubulin

Of the three types of cytoskeleton which can be involved in cell mobility?

Microfilaments

__ helps organize microtubules.

Centrosome

Centrioles form the basis of ___ and ___

cilia and flagella

Nucleus

Largest organelle; contains the genetic library of blueprints for synthesis of nearly all cellular proteins

The nucleus has three main structures:

1. Nuclear envelope

2. Nucleoli

3. Chromatin

Nuclear envelope

Double-membrane barrier that encloses the jelly-like fluid

Nucleolus/Nucleoli (multiple Nucleolus)

Contain cell blueprint and is involved in DNA and RNA synthesis

Chromatin is the __ and _ found inside the nucleus of a cell.

DNA and Protein

Chromatin contain histones, which help do what?

Histones help package the very long DNA so it can fit inside the nucleus.

Chromosomes are condensed ___

chromatin

The cell cycle has 2 periods

Interphase

Cell division (mitotic phase)

Interphase is the period from cell formation to cell division, when cell carries out its routine activities and ___ for cell division

prepares

Interphase has three subphases called what and what happens during them?

G1 - vigorous growth and metabolism

S (Synthesis) - DNA replication occurs

G2 - preparation for division

Where does cell division actually occur

M phase

M Phase contains what parts?

1. Mitosis

2. Cytokinesis

Stages of Mitosis

1. Prophase

2. Metaphase

3. Anaphase

4. Telophase

Prophase

Chromatin condenses, forming visible chromosomes

Each chromosome and its duplicate (called sister chromatids) are held together by a __

centromere

Metaphase

Centromeres of chromosomes are precisely aligned at cell’s equator The imaginary plane midway between poles is called metaphase plate

Anaphase

Centromeres of chromosomes split simultaneously. Chromosomes are pulled toward their respective poles by motor proteins of kinetochores

Telophase

Each set of chromosomes (at opposite ends of cell) uncoils to form chromatin. New nuclear membranes form around each chromatin mass

Late stage Mitosis Cyokinesis

Two daughter cells are pinched apart

Cell Cycle Checkpoints - G1

Restriction Checkpoint:

Makes sure the cell is ready for replication. If not ready then it prevents entry into S phase until all DNA damage is repaired. Makes cell go to G0

Cell Cycle Checkpoints - S

Makes sure DNA replicated propeerly. If it has not then the un-replicated DNA will be prevented entry into M phase (mitosis)

Cell Cycle Checkpoints - Mitosis checkpoint

Checks whether Mitosis is complete

What is the most important check point?

G1 checkpoint (restriction point) is the most important of the three major checkpoints. If cell does not pass, it enters G0, in which no further division occurs