DP Biology Unit 4: Protein synthesis & cell division - Core

genetic material

The cell's hereditary component and carries genetic information

genetic code

A set of rules that specifies how information stored in DNA is translated into the sequence of amino acids that make up proteins

nucleic acid

Polymers of nucleotides such as DNA and RNA

nucleotides

The building blocks (monomers) of nucleic acids

DNA (deoxyribonucleic acid)

Deoxyribonucleic acid, contained in the cell's nucleus, the molecule that carries genetic information for development and functioning of an organism

pentose sugar

A simple sugar made up of 5 carbons atoms, including the deoxyibose sugars that exist in DNA and RNA

nitrogenous base

A category of molecules that contain nitrogen and acts as a base including: guanine (G), adenine (A), thymine (T), cytosine (C) and uracil (U)

phosphate group

A functional group made up of phosphorus and oxygen

purines

Nitrogenous bases that have two rings in their structure

pyrimidines

Nitrogenous bases that have one ring in their structure

RNA world hypothesis

Theory that suggests that life on Earth may have initially evolved through the use of RNA instead of DNA as its genetic material

deoxyribose

A sugar that lacks a hydroxyl group on carbon number 2 in its structure and is a component in DNA

ribose

A sugar that has a hydroxyl group on carbon number 2 in its structure

complementary base pairing

Refers to the specific pairing of nucleotide bases in DNA and RNA molecules

replication

Copying of the DNA to double its amount and prepare the cell for division

gene expression

The process by which genetic information is used to produce RNA and proteins

gene

A segment of DNA that codes for a specific protein

sugar-phosphate backbone

the alternation of ribose or deoxyribose sugars with phosphate groups that essentially forms the main stucture holding the nitrogenous baes in their sequence position

semi-conservative

The mechanism of DNA replication where each single strand is used as a template for the assembly of a new polymer of nucleotides due to complimentary base pairing, thus ensuring a high degree of accuracy in copying

helicase

An enzyme that unwinds and separates the DNA double helix during DNA replication

DNA polymerase

An enzyme responsible for synthesising DNA molecules during DNA replication

polymerase chain reaction (PCR)

A laboratory technique used to amplify a specific DNA sequence, producing multiple copies of it

primers

A short DNA or RNA sequence that serves as a starting point for DNA synthesis by DNA polymerase

Taq polymerase

A heat-stable DNA polymerase commonly used in PCR reactions

denaturation phase (of PCR)

The initial step of PCR, where the DNA template is heated to separate the two strands

annealing phase (of PCR)

The second step of PCR, where the temperature is lowered to allow the primers to bind to complementary sequences on the DNA template

extension phase (of PCR)

The third step of PCR, where DNA polymerase extends the primers by synthesising new DNA strands

gel electrophoresis

A technique used to separate and analyse DNA fragments based on their size and charge using an electric field and a gel matrix

restriction endonucleases

Enzymes that recognise specific DNA sequences and cut the DNA at those sites, often used in genetic engineering and DNA analysis

short tandem repeats (STRs)

Sections of DNA containing repeated units that are 2 to 7 base pairs in length, with the number of repeats varying among individuals

RNA polymerase

Enzymes that use a DNA template to synthesise RNA

template or antisense strand

The DNA strand that is used as a template during transcription to synthesise a complementary RNA molecule

coding or sense strand

The DNA strand that has the same sequence as the RNA molecule produced during transcription, except with thymine (T) replaced by uracil (U)

free RNA nucleotides

Individual RNA nucleotides (adenine, uracil, cytosine, and guanine) that are available in the cell for use during transcription to create the complementary RNA molecule

complementary base pairing

Refers to the specific pairing of nucleotide bases in DNA and RNA molecules (via hydrogen bonds)

codon

A set of three adjacent nucleotides (hence triplet code) in DNA or mRNA that code for a particular amino acid

anticodon

A sequence of three nucleotides in tRNA that is complementary to a specific codon in mRNA, allowing the tRNA to recognise and bind to the corresponding codon

degeneracy

Refers to the redundancy in the genetic code, which allows for multiple codons to code for the same amino acid

universal

Referring to the fact that the genetic code is nearly identical in all organisms, with most codons specifying the same amino acids

initiation

The stage of translation where the ribosome assembles and starts the synthesis of a new polypeptide chain

elongation

The stage of translation where the growing polypeptide chain is extended by the addition of amino acids

mutation

A change in the sequence of DNA

insertion (mutation)

A type of genetic mutation where one or more nucleotides are added to a DNA sequence. This can result in a shift in the reading frame, causing a frameshift mutation

deletion (mutation)

A type of genetic mutation where one or more nucleotides are deleted from a DNA sequence. This can also result in a frameshift mutation, as the deletion causes a shift in the reading frame

frameshift (mutation)

Occur when insertions or deletions of nucleotides disrupt the reading frame of a gene sequence

substitution (mutation)

A type of genetic mutation where one nucleotide is replaced by another in a DNA sequence

silent mutation

A type of mutation that does not result in any change in the amino acid sequence of a protein due to the degeneracy of the genetic code

sickle cell anaemia

A genetic blood disorder that is caused by a mutation in the haemoglobin gene, resulting in abnormal haemoglobin

same-sense

base substitution that change one codon for an amino acid into another codon for the same amino acid

non-sense

change a codon for an amino acid into a stop codon

mis-sense

change a codon for an amino acid into into a codon for a different amino acid

single-nucleotide polymorphisms (SNPs)

Replacement of a single nucleotide with another, producing variation within a species. These are often found in non-coding regions of DNA

synonymous substitutions

A neutral mutation that does not change the amino acid sequence due to the degeneracy of the genetic code

non-synonymous substitutions

A mutation that causes a change in the amino acid sequence

mutagens

Agents that can cause mutations

ionising radiation

High energy radiation that can knock electrons out of orbit, leading to the formation of charged particles (ions) and potentially causing damage to biological tissue

deamination

A chemical reaction in which an amino group is removed from a molecule

germ cells

Cells that develop into gametes

somatic cells

Cells in the body that are not involved in the production of sperm or egg cells

silent mutation

A type of mutation that does not result in any change in the amino acid sequence of a protein due to the degeneracy of the genetic code

genetic variation

Differences found in the DNA sequences of individuals within a population

Commercial genetic tests

Provide individuals with information about their potential health and disease risks

parent or mother cell

A cell that divides during cell division

daughter cell

A cell that is produced by cell division

cytokinesis

The physical division of a cell into two daughter cells

cleavage furrow

contractile ring

A ring-like structure composed of actin and myosin filaments that forms during cell division in animal cells to physically separate the cytoplasm during cytokinesis

cell plate

A structure that forms during cytokinesis in plant cells that eventually develops into the cell wall that separates the daughter cells

oogenesis

The production of mature ovum

polar body

A small cell that is formed during oogenesis containing a discarded set of chromosomes and minimal cytoplasm

budding

A form of asexual reproduction in which a new individual organism develops as an outgrowth or bud from the parent organism, eventually detaching to become an independent organism

haploid

cells with nuceli containing only one set of chromsomes (n)

diploid

cells having two sets of chromosomes (one from each parent organism) (2n)

asexual reproduction

A form of reproduction that occurs without gametes and results in individuals who are genetically identical to the parent organism

sexual reproduction

A form of reproduction that involves gametes and results in individuals who are genetically unique from each other and the parent organism

reduction division

Involves halving the chromosome number before the nucleus is divided in two

prophase

The first stage of mitosis, involving condensation of chromosomes, breakdown of the nuclear membrane and formation of the spindle

metaphase

The second stage of mitosis or meiosis, involving pairs of homologous chromosomes aligning at the metaphase plate

anaphase

The third stage of mitosis, involving the spindle fibres pulling sister chromatids to opposite poles of the cell

telophase

The final stage of mitosis, involving decondensation of chromosomes and reformation of the nuclear membrane

sister chromatids

Two identical copies of a chromosome, formed by DNA replication and attached to each other at the centromere

centromere

Central region of a chromosome pair where two copies of the same chromosome remain attached to each other

supercoiled

The tightly twisted and condensed form of DNA that enables efficient packaging within the cell

condensed

Referring to DNA that is tightly packed and organised

microtubules

Long, thin, cylindrical fibrous proteins that form the spindle apparatus during cell division

microtubules motors

Specialised proteins that bind to microtubules and hydrolyse ATP to provide the energy to move chromosomes to either pole of the cell during nuclear division

spindle

Microscopic protein structures that aid in the movement and separation of chromosomes during cell division

microtubule organising centres (MTOCs)

Structures within cells that regulate the formation and organisation of spindle fibres

centrosomes

Structures found in animal cells that organise and form the mitotic spindle

centrioles

Cylindrical organelles that help to establish and organise the microtubules, playing an important role in cell division