Bio final

What is a cell?

The smallest unit of structure and function in all living things

What is every cell enclosed in?

A plasma cell membrane (to maintain an internal environment)

What must each cell maintain?

Homeostasis (by performing the life processes)

What are organelles?

Structures within cells that have specialized functions

What do we call cells with specific functions (as they become tissues?)

Specialized/differentiated cells

What do we call undifferentiated/unspecialized cells?

Stem cells

What do prokaryotic and eukaryotic cells have in common?

Both contain DNA, RNA, fluid (cytoplasms), ribosomes, utilize energy, and use the same biomolecules (monomers, fatty acids, amino acids, and nucleotides)

What do golgi bodies do?

They package and prepare materials to be sent/secreted out of the cell

What does a nucleus do?

It contains genetic materials (DNA)

What do lysosomes do?

They contain enzymes that digest food, old cell parts, and bacteria

What do ribosomes do?

Synthesize proteins

What does endoplasmic reticulum do?

It is a series of membranes that allows materials to travel throughout cells (and synthesizes important biomolecules)

What do nuclear membranes do?

They surround nuclei and contain pores

What do vacuoles do?

They hold water, food and waste

What does a nucleolus do?

It makes ribosomes and is found inside the nucleus

What does a cell membrane do?

It is a phospholipid membrane that surrounds all cells, controls the entry of materials into and out of cells, and maintains homeostasis

What do mitochondria do?

They supply energy through cellular respiration by creating ATP

What do chloroplasts do?

They make glucose for plants (this is where photosynthesis occurs) using photosynthetic pigments

What does cytoplasm do?

It is a jellylike, liquid substance within cells that contain nutrients

What do cell walls do?

They shape and support plant cells (and some bacteria cells) and are made of cellulose (fiber)

What do centrosomes do?

They help make spindle fibers (are made of microtubules) in animal cells, which are involved in chromosome movement during cell division

What do centrioles do?

They organize microtubules during cell division

What do cytoskeleton fibers do?

It serves as a structure that helps cells maintain their shape and internal organization (allowing cells to carry out essential functions)

What do microtubules do?

They help support the shape of a cell (by forming a rigid skeleton), help move chromosomes in cell division, and provide a framework for organelles/vesicles to move within the cell (using motor proteins)

What do microfilaments do?

They support cell structure and are involved in separating cells during cell division, allowing for motility and changes in cell shape.

What do intermediate fibers do?

They stabilize a cell's structure by resisting tension (preventing the tissues from tearing) and help anchor the nucleus and other organelles

What do leucoplasts/amyloplasts do?

They synthesize starch/amylose, lipids and proteins in plant cells

What is the order of the 3 proteins that make up the cytoskeleton (from smallest to largest)?

Microfilaments, intermediate fibers, and microtubules

What are microfilaments made of?

They are thin, threadlike strands made of ACTIN (a contractile protein)

What does the actin in microfilaments allow it to do?

It allows the microfilaments to move the cytoplasm around the cell (and allow the cell to change shape)

What are transport vesicles?

Small, membrane enclosed sacs that move molecules, secrete substances, digest materials, or regulate the pressure in the cell

What are intermediate fibers made up of?

Fibrous keratin (a structural protein)

Where are microfilaments typically located?

They are attached to cell membranes, allowing it to move and change shape

Where are intermediate fibers usually located?

Within the cell (to keep it from tearing and to anchor the nucleus and other organelles)

What do peroxisomes do?

They break down fatty acids and other molecules through oxidative reactions (and produce hydrogen peroxide as a byproduct)

Where are microtubules found in (in addition to the cytoskeleton)?

In the internal structure of cilia and flagella, as well as in centrosomes (to make spindle fibers) near the nucleus of animal cells

What is a flagellium?

A long, whip-like structure involved in movement (they move in a propeller like motion)

What is the cilia?

A short, hair-like projection that is involved in "sweeping" motions (back and front beating) and is sometimes used for movement in protists

What does the rough endoplasmic reticulum do?

It is covered with ribosomes and synthesizes proteins that are secreted

What does the smooth endoplasmic reticulum do?

It synthesizes lipids (phospholipids, steroid hormones, cholesterol, oils), metabolizes carbohydrates, regulates calcium ion storage within cells (especially in muscle cells) and utilizes detoxification processes

What are detoxification processes?

Processes in cell that break down toxins within the body (which smooth ER often utilize), such as drugs and alcohol

What organelles are used in biological transport?

The endoplasmic reticulum, golgi apparatus, and transport vesicles (all of which help transport substances)

What organelles are used in respiration (breathing, not cellular respiration)?

Mitochondria (which provide lungs - which are technically muscles - with energy)

What organelles are used in nutrition?

Chloroplasts in plants and lysosomes in animals (the former makes food and the latter breaks down food)

What organelles are used in synthesis?

Ribosomes and the endoplasmic reticulum (rough and smooth)

What organelles are used in excretion?

The cell membrane and lysosomes (the former allows waste to exit cells and the latter breaks down waste)

What organelles are used in reproduction?

The nucleus and centrosomes (which provide DNA and allow cell division)

What organelles are used in growth?

The nucleus and centrioles/centrosomes

What organelles are used in regulation?

The nucleus and cell membrane (which control all metabolism)

What are free floating ribosomes (or cytoplasmic ribosomes)?

Ribosomes that synthesize proteins that will be utilized in the cell (they exit through nuclear pores without traveling through lumen of the rough ER and are not secreted)

What is secretion?

The process by which cells release substances (hormones, enzymes, proteins, waste, etc) to the outside of the cell or into the body for a specific purpose

What do phospholipids do in cell membranes?

They make up the majority of cell membranes and allow certain substances to travel in and out of cells (since they are amphipathic/partially polar and nonpolar)

What are phospholipids composed of?

One glycerol, 2 fatty acids (which can be saturated or unsatured) and one phosphate group

What parts of cell membranes are polar and nonpolar?

The phosphate heads are polar and the lipid tails are nonpolar

What does cholesterol do in cell membranes?

It regulates their fluidity, which stabilizes them

What types of cells contain cholesterol?

Animal cells only (our liver produces cholesterol, and only animals have livers)

What is the plasma membrane (cell membrane) described as?

A fluid mosaic model (that is constantly moving)

What types of proteins are found in cell membranes?

Peripheral, structural, transport, enzymes, glycoproteins, receptors, transmembrane, and cell junctions

What do enzymes attached to cell membranes do?

Their active sites face the cytoplasmic (inside) side of a cell to catalyze reactions

What are peripheral proteins and what do they do?

Proteins bound to the outer layer of cell membranes, which help cells communicate, maintain their shapes, and transport substances

What are integral proteins?

Proteins that penetrate the hydrophobic layer of cell membranes (and are embedded within the plasma membrane)

What are transport proteins?

Proteins that help move substances across cell membranes (such as protein channels, carriers, and pumps)

What do glycoproteins and glycolipids do?

They perform cell recognition by determining if a substance belongs to the cell or not (and signal for an immune attack if they identify a foreign substances)

What are receptor proteins and what do they do?

They are integral proteins that activate (when they receive ligands) a signal transduction pathway

What are ligands?

Molecules that bind to receptors (such as hormones or neurotransmitters)

What are signal transduction pathways?

A series of specific reactions in the cell (often caused by receptors on cell membranes)

What do structural membrane proteins do?

They attach to the cytoskeleton (microfilaments) and extracellular matrix (outside of cell) to help maintain cellular shape and assist in movement

What molecules can easily pass through cell membranes?

Nonpolar molecules (such as O2 and CO2)

What kinds of molecules need a transport protein in the membrane to pass through it (in passive transport)?

Polar molecules (such as glucose and charged ions like Na+ and Cl-)

What are carrier proteins?

Specialized transport proteins that change shape during the transport process

What are transmembrane proteins and what do they do?

Integral proteins that span the entire membrane (some are "curly") and stick out of the phosphate heads

What must there be for molecules to move across a membrane?

A concentration gradient (difference in [chemical] in and out of a cell)

What is passive transportation?

Transportation (through a membrane) from [high] to [low] that does not require energy (it is "down" or "with" the gradient)

What happens to the energy of molecules undergoing passive transportation?

They release (potential) energy because the molecules move from a higher to a lower concentration (since the move "down," their potential energy decreases) and entropy increases (as molecules spread out)

What is active transport?

Transportation (through a membrane) from [low] to [high] that does require energy (atp); (it travels "against" the gradient)

What are the two types of passive transport?

(Simple) diffusion and facilitated diffusion

What is diffusion?

The movement of molecules (across a membrane) from a region of [high] to [low] concentration.

How do substances travel through cell membranes in facilitated diffusion?

Because they are polar and can't pass through the lipid layer on their own, they get attracted to protein channels or carriers (from charges) and pull them through the membrane

Are protein channels and carriers specific to certain substances?

Yes (they attract specific chemicals/substances/monomers)

What is osmosis?

The passive diffusion of water across a membrane using protein channels called aquaporins

What are aquaporins?

Protein channels that attract water to get it through cell membranes (they are used in osmosis)

What is dynamic equilibrium?

A state where there is an equal [molecule] on both sides of a cell membrane (molecules are still moving across the membrane, but there is no net activity)

Why is it important for our bodies to never reach dynamic equilibrium?

If there is no net change in our cells, there is no activity or energy flowing in and out of our bodies (meaning our organs are failing and we are dead)

Why can't cells use glucose directly for energy?

Because it is a large molecule with a lot of stored energy, a cell would get damaged if it attempted to break it down all at once (it would also be inefficient)

What is the ATP cycle?

A cycle that slowly breaks down glucose to phosphorylate ATP (whose bonds can be broken to generate energy for the life processes)

What is the formula for photosynthesis?

6CO2 + 6H2O + sunlight energy --> C6H12O6 + 6O2

What is the formula for cellular respiration?

C6H12O6 + 6O2 -> 6CO2 + 6H2O + 32ATP

What are the products of aerobic respiration?

6 carbon dioxide, 6 water, and ~32 ATP

What organisms perform cellular respiration?

All organisms

What organisms perform photosynthesis?

Autotrophs (plants and some bacteria)

What are the products of anaerobic respiration?

6 carbon dioxide, 6 water, and 2 ATP

What are pigments?

Substances that absorb visible light (to perform photosynthesis) of various wavelengths

What type of relationship do wavelengths and energy have?

An inverse relationship

What light is best for photosynthesis?

White light (which contains all the types of visible light); if not, then red or blue light

How does energy flow in an ecosystem?

In one direction

How do nutrients flow in an ecosystem?

They are recycled by decomposers (detritivores)

How much energy is transferred from each trophic level to the next?

10% (5-20%)

What is energy used for at each trophic level?

It is used to perform the life processes, while some of it is lost to heat, excreted, or assimilated

What is mutualism?

A symbiotic relationship where both organisms benefit (ex: bees and flowers)

What is commensalism?

A symbiotic relationship where one organism benefits while the other is unaffected (ex: whales and barnacles)