Biology Q2

diffusion

the net movement of molecules or ions from a region of higher concentration to a region of lower concentration down a concentration gradient, as a result of the random movements of particles

facilitated diffusion

the diffusion of a substance through a transport protein in a cell membrane

Channel protein

a membrane protein of fixed shape which has a water-filled pore through which selected hydrophilic ions or molecules can pass by facilitating diffusion or active transport

Carrier protein

a membrane protein which changes shape to allow the passage into or out of the cell of specific ions or molecules by facilitated diffusion or active transport

osmosis

the net diffusion of water molecules from a region of higher water potential to a region of lower water potential

water potential

a measure of the tendency of water to move from one place to another

protoplast

the living contents of a plant cell, including the cell surface membrane but excluding the cell wall

plasmolysis

the loss of water from a plant or prokaryote cell to the point where the protoplasm shrinks away from the cell wall

incipient plasmolysis

the point at which plasmolysis is about to occur when a plant cell or a prokaryote cell is losing water

active transport

the movement of molecules or ions through transport proteins across a cell membrane, against their concentration gradient, using energy from ATP

sodium-potassium pump (Na+-K+ pump)

a membrane protein that moves sodium ions out of a cell and potassium ions into it, using ATP

endocytosis

the bulk movement of liquids or solids into a cell, by the infolding of the cell surface membrane to form vesicles containing the substance

exocytosis

the bulk movement of liquids or solids out of a cell, by the fusion of vesicles containing the substance with the cell surface membrane

phagocytosis

bulk uptake of solid material

pinocytosis

bulk uptake of liquid

phagocyte

a type of cell that ingests and destroys pathogens or damaged body cells

chromatid

one of two identical parts of a chromosome

mitosis

the division of a nucleus into two so that the two daughter cells have exactly the same number and type of chromosomes as the parent cell

cell cycle

the sequence of events that takes place from one cell division until the next

kinetochore

a protein structure found at the centromere of a chromatid to which microtubules attach during nuclear division

asexual reproduction

the production of new individuals of a species by a single parent organism

telomere

repetitive sequence of DNA at the end of a chromosome that protects genes from the chromosome shortening that happens at each cell division

stem cell

a relatively unspecialized cell that retains the ability to divide an unlimited number of times, and which has the potential to become a specialized cell

cancers

a group of diseases that result from a breakdown i. the usual control mechanisms that regulate cell division

mutation

a random change in the base sequence of DNA, or in the structure and/or number of chromosomes

carcinogen

a substance or environmental factor that can cause cancer

nucleotide

a molecule consisting of a nitrogen-containing base, a penthouse sugar, and a phosphate group

polynucleotide

a chain of nucleotides joined together by phosphodiester bonds

dinucleotide

two nucleotides joined together by a phosphodiester bond

phosphodiester bond

a bond joining two nucleotides together

complementary base pairing

the hydrogen bonding of A with T or U and of C with G in nucleic acids

DNA polymerase

an enzyme that copies DNA

leading strand

during DNA replication, the parent strand that runs in the 3’ to 5’ direction is copied to produce the _______.

lagging strand

during DNA replication, the parent strand that runs in the 5’ to 3’ direction is copied to produce the ___________.

DNA ligase

an enzyme that catalyzes the joining together of two nucleotides with covalent phosphodiester binds during DNA replication

semi-conservative replication

the method by which a DNA molecule is copied to form two identical molecules, each containing one strand from the original molecule and one newly synthesized strand

gene

a length of DNA that codes for a particular polypeptide or protein

transcription

copying the genetic information in a molecule of DNA into a complementary strand of mRNA

translation

a stage in protein synthesis during which a sequence of nucleotides in a molecule of mRNA is converted into a corresponding sequence of amino acids in a polypeptide chain

codon

sequence of three bases on an mRNA molecule that codes for a specific amino acid or for a stop signal

anticodon

sequence of three unpaired bases on a tRNA molecule that binds codon on mRNA

gene mutation

a change in the base sequence in part of a DNA molecule

chromosome mutation

a random and unpredictable change in the structure or number of chromosomes in a cell

frame-shift mutation

a type of gene mutation caused by insertion or deletion of one or more nucleotides, resulting in incorrect reading of the sequence of triplets in the genetic code due to a shift in the reading frame

vascular system

a system of fluid-filled tubes, most commonly used for long distance transport in living organisms

vascular

a term referring to tubes of vessels

xylem

a tissue containing tubes called vessels and other types of cell, responsible for the transport of water and mineral salts through a plant and for support

phloem

a tissue containing tubes called sieve tubes and other types of cell, responsible for the transport through the plant of organic solutes

vascular tissue

a tissue in plants consisting mainly of xylem and phloem but also containing sclerenchyma and parenchyma cells

dicotyledon

flowering plants that contain an embryo with two cotyledons in their seeds

vascular bundle

the fundamental transport unit in vascular plants, functioning like a plant's circulatory system

parenchyma

a basic plant tissue typically used as packing tissue between more specialized structures

collenchyma

a modified form of parenchyma in which the corners of the cells have extra cellulose thickening, providing extra support

epidermis

the outer layer of cells covering the body of a plant or animal

endodermis

the layers of cells surrounding the vascular tissue of plants

sclerenchyma

a plant tissue consisting of thick-walled cells with a purely mechanical function

lignin

a hard material made by plants and used to strengthen the cells covering walls of certain types of cell

transpiration

the loss of water vapor from a plant to its environment

mesophyll

the region of a leaf between the upper and lower epidermis

stoma

a pore in the epidermis of a leaf

xerophyte

a plant adapted to survive in conditions where water is in short supply

cuticle

a layer covering, and secreted by, the epidermis

symplast pathway

the living system of interconnected protoplasts extending through a plant, used as a transport pathway for the movement of water and solutes

apoplast pathway

the non-living system of interconnected cell walls extending throughout a plant, used as a transport pathway for the movement of water and mineral ions

xylem vessel element

a dead, lignified cell found in xylem specialized for transporting water and for support

xylem vessel

a dead, empty tube with lignified walls, through which water is transported in plants

casparian strip

band that stops water from moving through the apoplast

natural kinetic energy

What causes the random movement of molecules/ions?

equilibrium

A state where there is no net movement of molecules because movement in opposite directions is equal.

Oxygen, carbon dioxide, and water

What molecules or ions can pass through cell membranes by diffusion?

Steepness of the concentration gradient, temperature, surface area, nature of molecules or ions

What four factors affect the rate of diffusion?

Number of channel/carrier proteins

What factors affect the rate of facilitated diffusion?

solute

a substance that is dissolved in a solvent

solvent

the liquid that dissolves a solute to form a solution

solution

homogeneous mixture formed when a solute dissolves in a solvent.

dilute

a low concentration of solute dissolved in a solvent

concentrated

a large amount of solute dissolved in a given amount of solvent.

The concentration of the solution, pressure

What two factors affect water potential?

KiloPascals

unit of water potential

0 kPa

water potential of pure water

-800 kPa

Which has the lower water potential: –200 kPa or –800 kPa?

Turgid

A plant cell is _____ when it has absorbed water by osmosis and is swollen with a high turgor pressure.

Plasmolysed

A plant cell is ______ when it has lost water by osmosis, causing the cell membrane to pull away from the cell wall.

3

How many sodium ions are pumped out of the cell?

2

How many potassium ions are pumped into the cell?

negative

For Na+-Ka+ pump, the inside of the cell becomes more ______ than the outside.

identical

Sister chromatids are __________ copies of one chromosome.

1.8

The total length of DNA in one human cell is approximately __________ meters.

6

The diameter of the nucleus is about __________ μm.

histones

DNA is wrapped around proteins called __________.

scaffolding

A precise _____ made of protein molecules prevents the DNA from getting tangled up into nots.

cytokinesis

Cell splits into two cells

2

number of daughter cells produced

prophase

Nuclear membrane disappears in _______.

metaphase

Chromosomes line up at equator in _____.

centromeres

Spindle fibers attach to ______.

anaphase

Sister chromatids separate and chromatids move to opposite poles in _________.

telophase

Nuclear membrane reforms in ________.

DNA replication

What happens in the S phase (synthesis phase)?

G1

RNA, enzymes and other proteins are made; cell becomes committed to dividing or not