bio

DNA

Instructions that tell cells how to work.

Nucleic Acid

A molecule like DNA or RNA that carries genetic info.

Chromosome

A bundle of DNA found in the nucleus.

Gene

A part of DNA that gives instructions for one trait.

Nucleotide

The building block of DNA (made of sugar, phosphate, and a base).

DNA Bases (A, T, G, C)

Letters that pair up (A-T, G-C) and make the code in DNA.

Replication

Copying DNA before a cell divides.

RNA

A copy of DNA used to make proteins.

RNA Bases (A, U, G, C)

A pairs with U, G pairs with C in RNA.

mRNA

Carries the message from DNA to the ribosome.

tRNA

Brings amino acids to the ribosome.

Transcription

Making mRNA from DNA.

Translation

Making proteins from mRNA.

Amino Acid

Building blocks of proteins.

Codon

A group of 3 mRNA bases that code for 1 amino acid.

Anticodon

A group of 3 tRNA bases that match with the mRNA codon.

Mutation

A change in the DNA sequence.

Point Mutation

One base is changed.

Frameshift Mutation

A base is added or deleted, shifting the whole sequence.

Karyotype

A picture of all the chromosomes in a cell.

Nondisjunction

When chromosomes don’t separate properly.

Trisomy 21

Having 3 copies of chromosome 21 (causes Down syndrome).

Diploid

A cell with two sets of chromosomes (46 in humans).

Haploid

A cell with one set of chromosomes (23 in humans).

Mitosis

Cell division that makes 2 identical body cells.

Meiosis

Cell division that makes 4 different sex cells.

Somatic Cell

A body cell.

Gamete

A sex cell (sperm or egg).

Allele

A version of a gene (example: blue or brown eyes).

Dominant

A trait that shows even if only one copy is present.

Recessive

A trait that shows only if two copies are present.

Homozygous

Two of the same alleles (AA or aa).

Heterozygous

Two different alleles (Aa).

Genotype

The genes an organism has.

Phenotype

The physical traits that show.

Pedigree

A family tree that shows how traits are passed on.

Autosomal Dominant

Trait appears if at least one dominant allele is present.

Autosomal Recessive

Trait only appears if two recessive alleles are present.

Evolution

Change in species over time.

Natural Selection

When traits that help survival become more common.

Overproduction

Having more offspring than the environment can support.

Variation

Differences between individuals.

Adaptation

A trait that helps an organism survive.

Selective Pressure

Something that affects survival (like predators or food).

Competition

Fighting for resources like food or mates.

Fitness

How well an organism survives and reproduces.

Speciation

The formation of new species.

Fossils

Remains of ancient life.

Comparative Embryology

Comparing embryos of different species.

Comparative Analogy

Comparing similar functions in different species.

Comparative Biochemistry

Comparing DNA or proteins of different species.

Homologous Structures

Body parts that look similar but have different uses.

Analogous Structures

Body parts that have similar functions but different structures.

Vestigial Structures

Body parts that no longer have a use (like human tailbone).

Cladogram

A diagram that shows how species are related.

Extinct

A species that no longer exists.

Common Ancestor

An early organism that two or more species came from.

Outgroup

A species that is less related to the others (used for comparison).