Genetics/Evolution

Alleles

Different versions of a gene that tell your body how to make traits like eye color or height.

Anaphase I

This is when, during cell division, pairs of chromosomes split apart and move to opposite sides of the cell.

Anaphase II

This is when the sister parts of chromosomes (called chromatids) are pulled apart in the second round of cell division.

Autosomes

These are the chromosomes that control most of your traits, like hair color, but are not the ones that determine if you're a boy or a girl.

Carrier

Someone who has a hidden gene for a certain trait (like a disease) but doesn't show it because they only have one copy of the gene.

Chromosomes

Tiny, thread-like structures inside cells that carry the information about how we grow and look. We get half from mom and half from dad.

Codominant Alleles

When two different versions of a gene show up together in a way that both are equally seen, like when both red and white flowers mix and make a red-and-white flower.

Crossing Over

When chromosomes swap parts with each other during cell division, making sure we get a mix of traits from both parents.

Dihybrid Cross

A type of experiment where we look at two different traits at once, like eye color and hair color, to see how they’re inherited.

Diploid

A cell that has two sets of chromosomes, one from mom and one from dad.

Dominant Allele

A gene that shows up in your body even if you only have one copy of it, like if you get a brown eye color gene from just one parent.

Down Syndrome

A condition where a person has an extra copy of chromosome 21, which can cause learning and physical differences.

Gene Transfer

Moving a gene from one organism to another, often used in science to help plants or animals have special traits.

Genes

Little pieces of information in our cells that decide what we look like and how we grow.

Genotype

The exact genes you have that make you who you are. It's like your DNA code.

Gregor Mendel

A scientist who studied how traits like flower color are passed down from parents to kids. He’s called the 'father of genetics.'

Haploid

A cell that has only one set of chromosomes, like an egg or sperm cell, so that when they join, they make a full set.

Hemophilia

A condition where someone's blood doesn’t clot properly, so they can bleed more easily. It’s usually passed down in families.

Heterozygous

When you have two different versions of a gene, like one gene for brown eyes and one gene for blue eyes.

Homologous Chromosomes

Chromosomes that are the same in shape and size, but you get one from your mom and one from your dad.

Homozygous

When you have two of the same version of a gene, like two genes for brown eyes.

Karyotyping

A way scientists look at all the chromosomes in your cells to see if there’s anything unusual, like an extra chromosome.

Meiosis

A special kind of cell division that makes eggs and sperm so that babies get one set of chromosomes from each parent.

Metaphase I

When chromosomes line up in the middle of the cell before they start moving to separate sides during meiosis.

Metaphase II

When chromosomes line up again in the middle of the cell in the second round of meiosis before being separated.

Multiple Alleles (e.g., Blood Type)

When there are more than two versions of a gene, like how there are A, B, and O blood types instead of just two choices.

Nondisjunction

When chromosomes don’t separate properly during cell division, leading to too many or too few chromosomes in the cells.

Pedigree Chart

A family tree that shows how certain traits are passed down through generations.

Phenotype

How a person or organism looks or behaves, like having brown hair or being tall. It’s the result of their genes.

Polyploid

An organism that has more than two sets of chromosomes. Some plants can have more than two sets!

Prophase I

The first step of cell division where chromosomes start to pair up and get ready to split.

Prophase II

The first step of the second round of cell division, where chromosomes get ready to split again.

Punnett Square

A tool scientists use to predict what traits the offspring might have based on the parents' genes.

Recessive Allele

A gene that only shows its effect if you have two copies of it, like blue eyes, which can only happen if both parents pass on the blue eye gene.

Recombinant DNA

DNA that has been changed by scientists to include genes from another organism, like adding a gene from one animal to another.

Segregation

The way chromosomes separate during cell division so that each new cell gets only one copy of each gene.

Sex Chromosomes

The chromosomes that decide if you're a boy or a girl (XX for girls, XY for boys).

Sex Linkage

When certain traits or diseases are passed down through the sex chromosomes, like colorblindness.

Synapsis

When chromosomes pair up with their matching partner before dividing, so they can swap pieces of DNA.

Telophase I

When the first round of cell division finishes and the chromosomes are at opposite sides of the cell, ready to split.

Telophase II

When the second round of cell division finishes and four new cells are created, each with half the number of chromosomes.

Trisomy

When someone has three copies of a chromosome instead of two, which can cause conditions like Down syndrome.

Acquired Characteristics

Traits you get during your life, like muscles from exercise, which you can't pass down to your kids.

Allopatric Speciation

When new species form because a group of animals or plants gets separated into different places and can no longer mate with each other.

Analogous Structures

Body parts in different animals that do the same job but are not from the same ancestor, like wings in birds and insects.

Antibiotic Resistance in Bacteria

When bacteria change and become strong against medicine (antibiotics), making it harder to treat infections.

Biological Species Concept

A way to define species: if two animals can mate and have babies that can also have babies, they’re the same species.

Directional Selection

When one extreme trait, like big size, becomes more common because it helps animals survive better.

Disruptive Selection

When both extreme traits, like big and small size, are favored, and the middle size is not.

Charles Darwin

The scientist who figured out how animals and plants change over time through natural selection.

Evolution

The process by which species change over time due to changes in traits passed down through generations.

Genetic Drift

Random changes in the traits of a population that happen by chance, not because they’re better for survival.

Homologous Structures

Body parts in different animals that are similar because they come from a common ancestor, like human arms and bat wings.

Hybrid

The baby of two different species, like a mule, which is the result of a horse and donkey mating.

Industrial Melanism in the Peppered Moth

When the color of moths changed in polluted areas because darker moths survived better against dark, sooty trees.

Mechanical Isolation

When two animals can’t mate because their body parts don’t fit together, like mismatched flower shapes and pollinators.

Morphological Species Concept

The idea that animals are different species if they look different enough, even if they can still mate.

Mutations (All Types)

Random changes in genes that can create new traits, and sometimes they help, hurt, or don't change anything at all.

Natural Selection

The process by which animals and plants that are better suited to their environment survive and reproduce more.

Postzygotic Barriers

Things that happen after two animals mate that prevent the baby from surviving or being able to have babies of its own.

Prezygotic Barriers

Things that stop animals from mating in the first place, like if they don’t mate at the same time.

Sexual Selection

When animals pick mates based on their traits, like bright feathers or big antlers, which help them attract mates.

Stabilizing Selection

When the average trait, like an average-sized...