Science Test

Adenine (A)
One of the four bases in DNA. Adenine pairs with thymine.

Allele
Different versions of the same gene.

Amino Acid
Small molecules that join together to make proteins.

Base Pair
Two matching DNA bases connected together (A-T or C-G).

Carrier
A person who has a recessive disease allele but does not have the disease.

Centromere
The middle part of a chromosome that holds chromatids together.

Chromatid
One half of a copied chromosome.

Chromatin
DNA and proteins packed together inside the nucleus.

Chromosome
A structure made of DNA that contains genes.

Codominance
When both alleles are fully shown at the same time.

Codon
A group of 3 bases that tells the cell which amino acid to add when making a protein.

CRISPR
A tool scientists use to edit DNA.

Cytosine (C)
One of the four bases in DNA. Cytosine pairs with guanine.

Deletion
DNA bases are removed.

DNA
The molecule that carries genetic information and instructions for living things.

Dominant Trait
A trait that appears when at least one dominant allele is present.

Frameshift Mutation
An insertion or deletion that changes how DNA is read.

Gene
A section of DNA that contains instructions for a trait or protein.

Genome
All the DNA in an organism.

Genetic Drift
Random changes in how common certain genes are in a population.

Genetic Engineering
Changing an organism’s DNA using technology.

Genotype
The gene combination an organism has.

GMO (Genetically Modified Organism)
An organism whose DNA has been changed by scientists.

Guanine (G)
One of the four bases in DNA. Guanine pairs with cytosine.

Haploid
Having one set of chromosomes.

Heterozygous
Having two different alleles for a gene.

Histone
A protein that helps package DNA neatly.

Homozygous
Having two identical alleles for a gene.

Homologous Recombination
The exchange of DNA between chromosomes during meiosis.

Inherited
Passed from parents to children through genes.

Insertion
Extra DNA bases are added.

Karyotype
A picture showing all the chromosomes in a cell.

Locus
The location of a gene on a chromosome.

Meiosis
Cell division that makes sex cells (egg and sperm).

mRNA (Messenger RNA)
RNA that carries instructions from DNA to ribosomes.

Missense Mutation
A mutation that changes one amino acid in a protein.

Mitosis
Cell division that makes two identical body cells.

Mutation
A change in DNA.

Non-coding DNA
DNA that does not make proteins.

Nonsense Mutation
A mutation that creates a stop codon too early.

Nucleolus
The part inside the nucleus where ribosomes are made.

Nucleotide
The basic building block of DNA and RNA.

Nucleus
The part of the cell that contains DNA.

Oncogene
A mutated gene that can cause cancer.

PCR (Polymerase Chain Reaction)
A lab method used to make many copies of DNA.

Pedigree
A family chart used to track inherited traits.

Phenotype
The physical traits you can observe.

Point Mutation
A change in one DNA base.

Polydactyly
Having extra fingers or toes.

Polygenic Trait
A trait controlled by many genes, like height or skin color.

Polymorphism
A common DNA variation among people.

Protein
Large molecules that do most of the work in cells and bodies.

Recessive Trait
A trait that only appears when both alleles are recessive.

Ribosome
The cell structure where proteins are made.

RNA
A molecule similar to DNA that helps make proteins.

Sex Chromosome
Chromosomes that determine biological sex (X and Y).

Sex-linked / X-linked Trait
A trait controlled by genes on the sex chromosomes.

Somatic Cells
Body cells that are not egg or sperm cells.

Stop Codon
A codon that tells the cell to stop making a protein.

Substitution
One DNA base is replaced by another.

Telomere
Protective ends of chromosomes that get shorter as cells divide.

Thymine (T)
One of the four bases in DNA. Thymine pairs with adenine.

Trait
A characteristic, such as eye color or height.

Transcription
Copying DNA information into RNA.

Translation
Using RNA instructions to build proteins.

Uracil (U)
A base found in RNA instead of thymine.

Virus
A tiny infectious particle that needs a host cell to reproduce.

Important Scientist

Gregor Mendel
The scientist known as the “father of genetics” because he discovered basic inheritance rules using pea plants.