Cells and Membrane Structure Quiz

AP Bio Mrs. Bose

Prokaryotes

Bacteria

No nucleus or membrane bound organelles

Eukaryotes

Protists, Fungi, Plants, Animals

Have a nucleus and membrane bound organelles

Genetic Material of Prokaryotes

Single circular chromosome w/ DNA

Genetic Material of Eukaryotes

Many rod shaped chromosomes w/ DNA

All cells have

A plasma membrane

cytosol

genetic material

ribosomes

Compartmentalization

Organelles create separate areas within the cell, each with a special environment and its own metabolic function

Allows for different reactions that need different conditions to happen separate from each other at the same time

Structure of Cell Membranes

Lipid bilayer, 2 layers of phospholipids w/ proteins embedded

Function of Cell Membranes

Separates cell from the outside

Allows for the exchange of nutrients and waste with environment, selects what goes in and out

Structure of Ribosomes

Contain rRNA and proteins

Function of Ribosomes

Makes proteins according to mRNA sequence

Free Ribosomes

Float in Cytosol, Produce proteins within cell

Bound Ribosomes

Attached to ER, make proteins for export from cell

Endomembrane System

Group of organelles that work together to create, modify, and transport lipids and proteins

Includes Nuclear envelope, lysosomes, vesicles, ER, and Golgi, which all have the same membrane structure

Endoplasmic Reticulum (ER) Structure

System of tunnels/tubes throughout cell

Endoplasmic Reticulum (ER) Function

Intracellular Transport

Smooth ER

No ribosomes

Lipid synthesis, detoxifies drugs and poisons

Rough ER

Has ribosomes

Takes protein by ribosomes and folds it into a 3D shape

Golgi Apparatus Structure

Stack of flattened fluid-filled membranes or sacs

Golgi Apparatus Function

Folding, chemical modification, packaging (into vesicles) and sends out proteins that were made in the cell

Path proteins take

Rough ER - Golgi - Vesicle - Final destination

Lysosome Structure

Membrane bound vesicle (from golgi)

contains hydrolytic enzymes for chemical digestion

Lysosome Function

Its enzymes can digest food (macromolecules), kill bacteria, and break down old cell parts

Mitochondria Structure

2 membranes create compartments for different reactions

The membranes (outer is smooth, inner is folded) provide more surface area for electron transport and ATP synthesis

Mitochondria Function

Converts nutrients (glucose) into ATP energy

Cytoskeleton Structure

Network of protein fibers and tubes

Cytoskeleton Function

Shapes and supports the cell. helps hold and move cellular materials

helps in cell division

Cytosol Structure

Jelly-like material, made of water, protein, salts, and organic molecules

Cytosol Function

Site of many chemical reactions

What is the Cytoplasm made of

Cytosol + organelles

Nucleus Structure

Surrounded by Nuclear Envelope

Pores - holes that allow things in and out of nucleus

Has DNA

Nucleus Function

Stores Genetic Info, which directs protein synthesis in the cell

Plant cell specific organelles

Cell Wall

Vacuoles

Chloroplasts

Cell Wall Structure

Made of cellulose in plants + hardening proteins, has pores

Cell Wall Function

Rigid Covering, strengthens and protects plant cells

Vacuole Structure

Large, membrane-bound vesicle

Vacuole Function

Storage of materials such as food, water, ion, and wastes

Chloroplast Structure

Has a double membrane + its own DNA

Thylakoid disks in stacks (grana) - membrane contains chlorophyll

Stroma surrounds thylakoid

Chloroplast Function

Absorbs sunlight for making sugar - photosynthesis

Endosymbiosis Theory

Prokaryotic cells were engulfed by larger prokaryotic cells

The smaller cells lived and reproduced inside the larger cell, eventually becoming one cell

Led to eukaryotic cells with mitochondria/chloroplasts

Evidence of Symbiosis

Mitochondria and chloroplasts

Resemble prokaryotic cells

Replicate similar to prokaryotes

DNA

Ribosomes similar in size to bacteria

Double phospholipid membrane

Similar size as bacteria

Why are cells so small?

Smaller cell means larger SA:V ratio, which leads to a better transport of nutrients (and waste out) which leads to more chemical reactions

SA:Volume ratio importance

The surface area of cell membranes is used to exchange materials

Big cells have more volume, so they need more stuff and make more waste, while having less surface area for transport

With less surface area, the less effective the process of exchanging materials is

Fluid Mosaic model

Made of mosaic of proteins embedded in fluid phospholipids, has carbs and steroids

Membrane held together by weak hydrophobic interactions

Lipids and some proteins can shift laterally

Phospholipid bilayer structure

Forms main fabric of membrane

it is amphipathic - has a hydrophobic head and hydrophobic tails

Membrane is mostly hydrophobic barrier, keeps hydrophilic molecules out

How does phospholipid type keep membrane fluid?

Phospholipids with unsaturated tails good when temperature decreases, it prevents it from being solid

Saturated tails are good when temperature increases, you don’t want it too fluidy

How does cholesterol type keep membrane fluid?

it limits excessive fluidity at high temperatures by slowing phospholipid movement

it hinders close backing of phospholipids at low temperatures

Integral Proteins

Embedded in membrane

Some have helical structure w/ hydrophilic aa’s on outside and hydrophobic aa’s in middle (transmembrane)

Some have hydrophilic channel to allow passing of hydrophilic molecules

Peripheral Proteins

NOT embedded

Held in place by the cytoskeleton

Hydrophilic

Provides stronger framework for animal cells

Functions of Membrane Proteins

Intercellular joining - cells hook together

Transport

Enzymes

Cell communication

Cell to Cell Recognition

Attachment to cytoskeleton or ECM - helps maintain cell shape

Cell Communication of Membrane Proteins

Receptor proteins have shape specific binding sites for a messenger like a hormone, message is relayed to cell interior

Cell to Cell recognition of Membrane Proteins

glycoproteins act as ID tags that can be recognized by proteins of other cell membranes

Carbohydrates in Cell Membranes Structure

Short chains, vary

types are glycolipids and glycoproteins

Carbohydrates in Cell Membranes Function

Cell-cell recognition, important in tissue rejection, blood types