Grade 12 Life Sciences - Scientific Skills and DNA

Vocabulary flashcards based on the provided lecture notes covering scientific skills, DNA, and meiosis.

Aim of an investigation

A statement that describes what will be done in the investigation or identifies the purpose of the investigation.

Planning steps for an investigation

A series of steps that outline how the investigation will be carried out.

Investigative question

A question based on observation of a phenomenon.

Hypothesis

An attempt to explain a phenomenon or a prediction/educated guess of what will happen in the investigation.

Variables

Factors that are tested to determine which one has an effect on the results.

Independent variable

The variable that is manipulated during an investigation; plotted on the X-axis.

Dependent variable

The variable that is measured during the investigation; plotted on the Y-axis.

Control

The variable that is kept constant throughout the investigation.

Trends

A statement where the progression of the results is stated usually in relation to time. Can also be described as the major changes that occur on the dependent variable in relation to the independent variable.

Evaluation of results

Evaluating the reliability and validity of the results obtained.

Validity

How fair the test was; fairness can be reached by keeping all variables constant except the one that is being tested

Reliability

If the results can be trusted such that if repeated similar results can be obtained.

Conclusion

Aims to link the results to the aim and hypothesis by explaining what the results tell us about what was being investigated.

Cytoplasm

Jelly-like fluid in a cell where most cellular reactions take place

Chromatin network

Network of genetic material found in the nucleus during interphase

Nucleoplasm

Contains free nucleotides

Nuclear membrane

Double membrane enclosing the nucleus with pores (nuclear pores)

Nucleolus

Manufactures ribosomal RNA

Ribosome

A complex molecule that serves as the site for protein synthesis

Nucleus

Carries genetic material

Nucleic acids

Organic molecules that are made up of nucleotides and control the synthesis of proteins

Nucleotides

Building blocks/monomers of nucleic acids.

Nucleotide

Made up of a phosphate ion, sugar molecule, and nitrogenous base

Chloroplastic DNA

Found in chloroplasts.

Mitochondrial DNA/mtDNA

Found in mitochondria.

Double helix

The natural shape of DNA

DNA replication

The process of making an identical copy of DNA (chromosome).

DNA profile

Unique pattern formed by the DNA fragments of an individual.

Ribosomal RNA (rRNA)

Forms part of the structure of the ribosome

Messenger RNA (mRNA)

Acts a messenger by carrying the genetic code from DNA in the nucleus to the ribosome in the cytoplasm to be used to synthesize proteins

Transfer RNA (tRNA)

Picks up amino acids in the cytoplasm and carries them to the ribosome during protein synthesis

Protein synthesis

The process whereby proteins are manufactured in living cells and is controlled by DNA and RNA

Base triplet

Three consecutive nitrogenous bases on the DNA strand.

Codon

Three consecutive nitrogenous bases on the mRNA strand.

Anticodons

Three exposed nitrogenous bases on a single tRNA.

Amino acids

Monomers or building blocks of proteins.

Peptide bond

A bond that holds amino acids together.

Polypeptide chain

Three or more bonded amino acids

Gene

Consists of a group of triplet bases that code for the synthesis of a protein

Template strand

Strand of DNA upon which another strand of DNA is built /mRNA is transcribed

Centrosome/centriole

Produces the spindle fibre

Spindle fibre

Contracts to pull chromosomes to opposite sides of the equator

Centromere

Joins/holds the chromatids together in a chromosome

Chromatid

Thread-like strands that make up a chromosome

Chromosome

A structure made up of two chromatids joined by a centromere

Maternal and paternal

Maternal relates to chromosomes or genetic material inherited from the mother while paternal relates to that inherited from the father

Homologous chromosomes

Chromosomes exist as single/individual chromosomes or they exist as part of a pair. As a pair they are referred to as homologous pairs/chromosomes.

Autosomes

The 22 pairs of chromosomes in the human karyotype that is not associated with gender

Gonosomes

The two pairs of chromosomes in the human karyotype that determine gender

Somatic cells

Which are body cell have two sets of chromosomes which are paired (homologous pairs)

Gametes

Sperm cells or ova which have a single set of chromosomes

Meiosis

Type of cell division that halves the number of chromosomes to form haploid gametes.

Interphase

A phase between consecutive cell divisions where DNA replication occurs.

Crossing Over and Chiasma (chiasmata)

Chromatids from each homologous chromosome overlap. The point where they overlap

Random arrangement of chromosomes

The chromosomes line up along the equator of the cell as homologous pairs where each pair of the homologous pair line up randomly on the equator independently of how other pairs line up

Separation of homologous chromosomes

During anaphase 1, the spindle fibre shortens/contracts thereby separating the homologous chromosomes as they move to the opposite poles of the spindle

Non-disjunction

Failure of one or more chromosomes to separate during meiosis