Download c) B2 topic 1 Glosssary of key words

Topic B2 Building Blocks of Cells
Light microscope
Instrument that magnifies specimens using light & lenses
Cells
Basic units of life in which many chemical reactions needed to sustain
life (eg respiration)
Cell membrane
Thin layer that forms a semi permeable barrier around the outside
surface of the cytoplasm of the cell. Controls movement of
substances in & out of the cell
Cytoplasm
Liquid gel that make sup most of the body of a cell. Is where many
chemical reactions take place
Nucleus
Contains DNA for making proteins, new cells and organisms. Also
controls the reactions of a cell.
Mitochondria
Site of cellular respiration where glucose is broken down using
oxygen to release energy. Needed for reactions in the cell
Cell wall
Relatively rigid structure that surrounds plant and bacterial cells.
Supports the cell & helps it to keep its shape
Cellulose
Cell walls are made up of tough cellulose which supports the cell &
helps it to keep its shape
Vacuole
Membrane bound space in the cytoplasm filled with cell sap, a store
of water & nutrients. Helps support the plant by keeping cells rigid
Chloroplasts
Organelle in plant cells that contains chlorophyll. Is where
photosynthesis takes place
Chlorophyll
Green substance in chloroplasts that absorbs energy from sunlight
Electron
microscope
Chromosomal DNA
Instrument that magnifies specimens using a ben of electrons
Plasmid DNA
A circle of extra DNA found only in bacterial cells
Flagella
Whip like protein found on the outside of a bacterial (and other) cells.
Beats back & forth for movement
Chromosomes
Thread like structure found in the nucleus of a cell. Carries the
genetic information
DNA that makes up the chromosomes of a cell
DNA
DNA
Molecule that makes up genes and chromosomes. Contains the
instructions for a cells growth & activity
Gene
A section of DNA that codes for a specific protein
Double helix
The spiral structure of a DNA molecule. Produced by two strands
joined by complementary base pairs
Bases
Adenine
Pair up in the same way because the molecules have a
complementary shape that match. Adenine + Thymine / Guanine +
Cytosine
A base (chemical found in DNA) that pairs with thymine
thymine
A base (chemical found in DNA) that pairs with adenine
Cytosine
A base (chemical found in DNA) that pairs with guanine
Guanine
A base (chemical found in DNA) that pairs with cytosine
Complementary
base pairs
Bases that pair up in the same way because the molecules have a
complementary shape that match. Adenine + Thymine / Guanine +
Cytosine
Hydrogen bonds
Base pairs are joined together by these (weak) hydrogen bonds
Genetic Engineering
Human Genome
Project (H)
A project to sequence (order) all of the base pairs of the human
genome. Involves Scientists from many different countries working
together
Genome (H)
All the genetic information (DNA) as a list in order of every base
Genetic
engineering
Process of removing a gene from one organism and inserting it into
the DNA in a call of another organism
Genetically
modified
Organisms (GMO)
Golden rice
An organism that has had a gene inserted from another species (eg
human insulin into a bacterium)
Beta-carotene
Substance in the human diet from which the body makes vitamin A
Herbicide
Biodiversity
Genetically engineered rice that produces beta-carotene in the rice
grains – turning them a golden yellow colour
Chemical that kills plants. Usually used on weeds
The variety of species present within a given area
Cell division
Diploid
A cells that has two sets of chromosomes. In humans, almost all celss
are diploid – except sperm & egg cells
Growth
To increase in size, length, mass and cell number
Mitosis
Division of parent cell that produces genetically identical diploid cells
DNA replication
When the chromosomes are copied before cell division occurs
Daughter cells
Cell produced from the division of a parent cell
Parent cell
A cell that divides to produce daughter cells
Asexual
reproduction
Formation of a new organism without fertilisation. Uses the process of
mitosis to create offspring identical to the parent
Sexual
reproduction
Formation of a new organism from the fertilisation of female gamete
(egg cell) by a male gamete (sperm cell) This individual is genetically
different from its parents
Gametes
Sex cells (sperm or eggs) produced in the reproductive organs my
meiosis
Haploid cells
A cell that has one set of chromosomes (a gamete)
Fertilisation
When two gametes fuse
Zygote
A fertilised egg cell
Meiosis
Division of a parent cell that produces two genetically different
haploid cells
Alleles
Different versions of the same gene. Eg alleles for eye colour blue or
brown
Technology & cell division
Clones
Individual created from a form of asexual reproduction. Produces
offspring that are genetically identical to the parent
Enucleated (H)
To remove the nucleus from a cell
Implanted (H)
To place the embryo into the uterus of a female animal to develop
Uterus (H)
The womb of a female organism
Surrogate mother
(H)
A female who is related to the embryo that is implanted in her womb
to develop
Embryonic stem
cells
A cell from an early stage of division of an embryo that can produce
almost any type of differentiated cell
Stem cell
An unspecialised cell that can divide to produce more stem cells or
different kinds of specialised cells
Differentiated
Specialise & develop into different types of cell
Adult stem cells
Stem cells found in differentiated tissue that can produce a few types
of differentiated cells
Making proteins, mutations & enzymes
Genetic code
The code produced by the sequence of bases in genetic material (eg
DNA)
Amino acids
A small molecule that is the building block of a protein
Protein synthesis
The building up of a protein molecule by joining together amino acids
Transcription (H)
What an strand of mRNA is produced by complementary pairing of
bases with one strand of DNA in the nucleus
Messenger RNA
Molecule formed during DNA transcription that carries the code from
the chromosome to the ribosome
Uracil (H)
A base only found in RNA with replaces the base thymine in DNA
Ribosome (H)
Small structures in the cytoplasm of a cell. Where mRNA is translated
into an amino acid
Base triplets /
codons (H)
Transfer RNA (H)
A group of three bases that code for a particular amino acid
Polypeptide (H)
A chain of amino acids that will form part of a protein
Mutation
A change in the base sequences of DNA (often as a result to exposure
to radiation)
Enzymes
A protein molecule made by living cells that speeds up the rate of a
reaction
Catalysts
A substance that speeds up the rate of a reaction without being used
up in the reaction
Digestion
The breakdown of large insoluble food molecules into small soluble
food molecules
Specific
Only one (eg one enzyme can catalyse the reaction of a particular
substrate molecule)
Active site
Site on an enzyme molecule that has a specific shape and holds the
substrate molecule during a reaction
Lock and key
model
Idea / hypothesis that describes the relationship of substrate to the
active site of an enzyme (helps explain how enzymes work)
Denatures
To break down / change shape (as protein denature with excess heat)
A small RNA molecule that transfers the correct amino acid to the
ribosome during translation (so the protein it codes for can be made
(synthesised))