IB Biology Cells Unit Flashcards

All Flashcards combined from cell unit

Organelle

specialized structure that performs important specific cellular functions within a cell

cell fractionation

technique in which cells are broken into pieces and the different cell parts are separated

ultracentrifugation

The second stage of cell fractionation when the fragments in filtered homogenate are separated in a machine called a centrifuge.

Plasma membrane

A selectively-permeable phospholipid bilayer forming the boundary of the cells

homogenization

when trying to separate cell organelles, a tissue containing cells is blended in a cold buffered solution isotonic to the cell cytoplasm

nucleus

double membrane organelle where transcription and production of mRNA takes place

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

Transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA. occurs in the nucleus of eukaryotic cells

translation

(genetics) the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm

metabolites

chemical products of metabolism

enzymes

Proteins that speed up chemical reactions

Lysosomes

single membrane bound cell organelle filled with enzymes needed to break down certain materials in the cell

phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

phagocytic vacuole

forms when microbe is engulfed and will fuse with a lysosome

mitochondria

a double membrane bound organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur.

Cytoskeleton

network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement. Not considered an organelle

Chloroplast

a double membrane bound organelle found in plant and algae cells where photosynthesis occurs

ribosome

organelle not bound by a membrane that is the site of protein synthesis

cell wall

not considered an organelle - outside of a plant cell. rigid structure made of cellulose that surrounds the cell membrane and provides support to the cell

flagella

membrane bound organelle that allows for movement of cells

Organelles with no membrane

Ribosomes

Free DNA in prokaryotes

Microtubules

Organelles with single membrane

Rough and smooth eR

Vacuole and Vesicles

Lysossomes

Golgi Apparatus

Organelles with double membrane

Chloroplasts

Mitochondria

Nucleus

Amyloplasts

Chromoplasts

SA:Volume ratio

Impacts the function of exchange surfaces in different organisms by determining the efficiency of exchange.

Multicellularity

Organisms composed of many cells - developed by cellular specialisation and division of labour.

Embryonic Stem Cells

Pluripotent stem cells derived from the inner cell mass of a blastocyst, an early-stage pre-implantation embryo (4/5 days)

Adult Stem Cells

Undifferentiated cells, found throughout the body after development, multiply by cell division to replace dying cells and regenerate damaged tissues. AKA somatic stem cells.

Induced Pluripotent Stem Cells

Stem cells derived from adult somatic cells. Reprogrammed to be pluripotent, they are similar to embryonic stem cells.

Totipotent

Cells with the greatest differentiation potential. Can divide to form any embryonic cell, as well as any extraembryonic cell.

Pluripotent

Can self-renew by dividing and can develop into the three primary germ cell layers of the early embryo and all body cells (but not extra-embryonic tissues such as the placenta).

Multipotent

Can develop into more than one cell type, but within the same lineage, e.g., stem cells in the bone marrow only make blood cells.

Unipotent

A cell that can differentiate into one specific cell type.

Morphogen

Signalling molecules that cause a change in cells during their development. Changes in concentration give rise to different effects, and therefore different cell types.

Stem Cell Niche

The microenvironment where stem cells are found and receive stimuli that determine their fate.

Differentiation

The process of changing from an undifferentiated stem cell into a specialised cell with a particular function.

Specialisation

The development of specific functions and structures within a cell, after it has differentiated.

Proliferation

Stem cells divide to form one daughter cell that remains a stem cell and a second that differentiates.

Progenitor Cell

Can produce only one cell type but unlike other body cells are able to self-renew.

Gene Expression

Changes in gene expression result in differentiation - some genes are turned on and others off.

Regeneration

The process of replacing or restoring damaged or missing cells, tissues, organs, and even entire body parts - stem cells are responsible for this.

What is the plasma membrane?

A selectively permeable membrane which is made up by a phospholipid bi-layer which includes polar heads and non-polar fatty acid tails. It is able to regulate what goes in and out of the cell.

Six functions of membrane proteins...

Transport things in and out of cell
Enzymatic activities
Attachment to cytoskeleton and extracellular matrix
Communication with other cells (identification)
Adhesion to other cells
Receptor proteins

Why is the plasma membrane described as a fluid mosaic model?

Has many parts that come together to make a whole and those parts constantly move.

What are glycoproteins? What is their function?

Membrane carbohydrates that are covalently bonded to proteins. Serve as "chemical ID" for the cell.

What are glycolipids? What is their function?

Membrane carbohydrates that are covalently bonded to lipids. Serve as "chemical ID" for the cell.

What is cholesterol? What is its function?

Cholesterol is a steroid and is mostly hydrophobic. It makes sure the plasma membrane is not too fluid, but fluid enough. It also prevents crystallization and restricts cellular motion.

Function of channel/carrier proteins

Passive transport across the membrane

Function of protein pumps

Active transport across the membrane

Function of enzymes

Used in cell surface reactions

Function of Adhesion proteins

Binding cells together

Function of receptor proteins

Hormone binding and recognition

How do the hydrophobic and hydrophilic properties of the phospholipid bilayer allow the membrane to maintain its structure?

Since the cell membranes are phospholipid bilayers, a double layer of molecules exist as a stable boundary between two aqueous compartments because the molecular arrangement shelters the hydrophobic tails of the phospholipids from water while exposing the hydrophilic heads to water.

What does selectively permeable (in the context of the plasma membrane) mean?

Some substances can cross the membrane, while others can't.

What is diffusion?

The spreading out of particles in liquids and gases that happens because the particles are in continuous random motion.

What is osmosis?

The diffusion of water across a selectively permeable membrane.

Distinguish between solute, solvent, and solution.

solute-
solvent-
solution-

Simple diffusion
1. Does it go with the concentration gradient?
2. Does it use a selectively permeable membrane?
3. Does it use membrane proteins?
4. Does it need ATP?

1. Yes
2. No/Yes
3. Yes
4. No

Osmosis
1. Does it go with the concentration gradient?
2. Does it use a selectively permeable membrane?
3. Does it use membrane proteins?
4. Does it need ATP?

1. Yes
2. Yes
3. Yes
4. No

Facilitated Diffusion
1. Does it go with the concentration gradient?
2. Does it use a selectively permeable membrane?
3. Does it use membrane proteins?
4. Does it need ATP?

1. Yes
2. Yes
3. Yes
4. No

Active Transport
1. Does it go with or against the concentration gradient?
2. Does it use a selectively permeable membrane?
3. Does it use membrane proteins?
4. Does it need ATP?

1. Against
2. Yes
3. Yes
4. Yes

What are the four types of membrane transport?

Simple diffusion, osmosis, facilitated diffusion, active transport

What method of membrane transport is used by water?

Osmosis through aquaporins

What method of membrane transport is used by non-polar molecules?

diffusion

What method of membrane transport is used by polar molecules?

facilitated diffusion

What method of membrane transport is used by any molecule against the concentration gradient?

active transport

What method of membrane transport is used by macromolecules?

endocytosis or exotycosis

What is a vesicle?

Vesicles are tiny sacs made of membranes, which are used to transport items around the cell.

What is the process of vesicle transport of a protein molecule through a eukaryote cell? Begin with protein synthesis in the Rough ER and finish with exocytosis through the plasma membrane.

Proteins are synthesized by ribosomes on the Rough ER. The protein then gets transported to the golgi apparatus, where it will get further modified and packaged for secretion. When it gets packaged, phospholipids from the golgi membrane will pinch off to form a vesicle around the protein. The vesicle will move to the plasma membrane, fuse with it, and then the protein will get released from the cell.

Exocytosis vs. Endocytosis...

In endocytosis, the cell takes IN biological membranes and particulate matter by forming new vesicles from the plasma membrane. Plasma membrane temporarily shrinks in size.
In exocytosis, the cell SECRETES certain biological molecules by the fusion of vesicles with the plasma membrane. Plasma membrane temporarily increases in size.

Compare and contrast facilitated diffusion and active transport.

Compare: Both types of transport use integral membranes to move molecules.
Contrast: Facilitated diffusion is a form of passive transport: no energy required because molecules are moving with their concentration gradient. Active transport requires energy because molecules are being moves against their concentration gradient.

Since carbs are big, the cell uses facilitated diffusion to help move them into the cell. What factors will increase the rate of carbohydrate uptake by the cell? Can the rate of carbohydrate uptake continually increase or will the rate eventually level out? Explain your reasoning.

The rate of carb uptake by the cell will be increased as the concentration of carbs on the outside of the cell increases. It adds to the concentration gradient and more carbs will be moved into the cell. However, the rate of uptake will NOT continually increase because there are only so many integral proteins that can facilitate the movement into the cell before they're all occupied. The rate will level out.

A property of the phospholipid bilayer that makes it both hydro phobic and philic

Amphipathic

Indirect Active Transport

When the movement of one molecule down its concentration gradient allows another molecule to be actively pumped against the concentration gradient. Eg: The sodium poassium pump.

During photosynthesis, where do the reactions that produce oxygen gas (O2) occur?

Photosystem II

During the light reactions, electrons within the pigments of the light-harvesting complex are moved to an excited state and then return to a ground state, releasing ___________. Eventually, chlorophyll A molecules in the reaction center get excited and lose _____________.

energy, electrons

During the reduction step of the Calvin cycle, an unstable six-carbon intermediate is formed and then split in half. What molecule is eventually formed that is used to make glucose?

G3P

The light reactions occur in the _____________ and the Calvin cycle occurs in the _____________.

thylakoid membrane, stroma

True or False: The electrons lost in photosystem I are replaced by the splitting of carbon dioxide and the electrons lost in photosystem II are replaced by the splitting of water.

False

What molecule attaches to RuBP in the Calvin cycle?

Carbon dioxide (CO2)

What process does the following equation describe?

Photosynthesis

Where does the process of photosynthesis occur within a leaf?

Mesophyll

Which of the following is produced during cyclic electron flow?

ATP

During the light reactions, ______ is produced in photosystem II and ______ is produced in photosystem I.

ATP and NADPH

calculation for magnification

measured length/scale bar label

calculation for actual size

measured length/magnification

three parts of cell theory

- the cell is the fundamental unit of structure and function in all living organisms.
- all organisms are made up of one or more cells.
- cells arise from other cells through cell division.

resolution

the ability to clearly distinguish between two separate points in a field of vision (smallest interval distinguishable)

light vs. electron microscope

electron microscopy is able to produce images of a higher resolution.

compound light microscopes

use multiple lenses to bend light and magnify images

electron microscope

a microscope that focuses a beam of electrons (by electromagnets) to magnify objects

structures common to ALL cells

plasma membrane, cytoplasm, DNA, ribosomes

what types of cells are prokaryotes?

archaea (unicellular), bacteria

prokaryotic cell structures

cell (plasma) membrane, cytoplasm, 70s ribosomes, cell wall, pili, capsule, flagellum, DNA

cell (plasma) membrane

responsible for regulating what materials move in and out of the cell - SELECTIVELY PERMEABLE

cytoplasm

gel-like fluid substance (mostly water with many dissolved molecules), site of METABOLIC REACTIONS

ribosome

builds proteins during TRANSLATION

cell wall

ONLY FOUND IN PLANTS - provides shape and allows the cell to withstand turgor pressure without bursting

nucleoid

prokaryotic cell DNA is "naked", which means that the DNA is not associated with proteins

difference in RIBOSOMES in prokaryotes and eukaryotes

prokaryotes - smaller 70s ribosomes
eukaryotes - larger 80s ribosomes

plasmid

ONLY IN PROKARYOTES - small, circular pieces of DNA that can be transferred from one prokaryotic cell to another.