Bio midterm!!

Natural Selection

The process where living things with traits that help them survive and reproduce are more likely to pass on those traits to their offspring. Over time, these helpful traits become more common in the population.

Adaptation

A trait or change that helps a living thing survive better in its environment. It can be a body part, behavior, or ability that makes life easier or safer.

Fitness

How well an organism can survive and have babies in its environment. The more babies it has that also survive, the higher this is

Variation

Differences between individuals in a group. These can be differences in looks, behavior, or traits like size or color.

Artificial Selection

When humans choose which plants or animals will reproduce based on traits they like, such as size, color, or behavior. This process leads to changes in the population over generations, as desirable traits become more common.

Cladogram

A diagram that shows how different species are related through common ancestors. It looks like a tree with branches and helps scientists understand how living things evolved.

Morphological Characteristics

The physical traits or features of an organism, like shape, size, color, or body structure. These help scientists describe and compare different living things.

Charles Darwin

A scientist who came up with the idea of natural selection. He explained how species change over time and evolve. His most famous book is On the Origin of Species, published in 1859.

Fossil

The preserved remains or imprint of a plant or animal that lived a long time ago. They help scientists learn about life in the past.

Evolution

The process by which living things change over many generations, developing new traits that help them survive and reproduce better in their environment.

Selective Pressure

Something in the environment that affects which traits help an organism survive and reproduce. It "pushes" populations to change over time by favoring certain traits.

Common Ancestor

A earlier species from which two or more different species have evolved. It’s like a shared “family member” in the distant past.

Molecular evidence (DNA)

Information from an organism’s genetic material that scientists use to compare and find out how closely related different species are. It helps show evolutionary relationships.

Species

A group of living things that are similar and can mate with each other to have babies that can also grow up and have babies.

Genetic Similarity

How much the DNA of two organisms is alike. The more alike, the more closely related they usually are.

What are the three main pieces of evidence for evolutionary theory?

Fossil evidence, Comparative anatomy, and Molecular biology.

What is Fossil Evidence?

proof from old bones or imprints that shows what past life was like and how living things have changed over time.

Comparative anatomy

the study of body parts in different animals to see how they are alike. It helps show if they share a common ancestor.

Molecular biology

the study of tiny parts inside cells, like DNA and proteins, to understand how living things work and how they are related.

Deoxyribonucleic acid

A molecule that carries genetic instructions for how living things grow and function.

Ribonucleic acid

A molecule that helps carry out the instructions in DNA, often by making proteins.

Nucleotide

A building block of DNA and RNA, made of a sugar, a phosphate, and a base.

Nitrogenous Base

A part of a nucleotide that holds genetic code; examples include A, T, C, G (or U in RNA).

Adenine

A nitrogenous base in DNA and RNA that pairs with thymine (T) in DNA and with uracil (U) in RNA.

Thymine

A nitrogenous base in DNA that pairs with adenine (A).

Cytosine

A nitrogenous base in DNA and RNA that pairs with guanine (G).

Guanine

A nitrogenous base in DNA and RNA that pairs with cytosine (C).

Double Helix

The twisted ladder shape of DNA.

Base pair rules

In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

Amino Acid

A small molecule that joins with others to build proteins.

Polypeptide

A chain of amino acids linked together to form a protein.

Protein

A molecule made of one or more polypeptides that does jobs in the body, like building tissues and speeding up reactions.

Enzyme

A protein that speeds up chemical reactions in the body.

Helicase

An enzyme that unwinds and separates DNA strands during replication.

DNA Polymerase

An enzyme that builds new DNA strands by adding nucleotides during DNA replication.

Mutation

A change or mistake in the DNA sequence.

P53

A protein that helps stop damaged cells from growing and can trigger repair or cell death.

mRNA

A type of RNA that carries the genetic code from DNA to make proteins.

Mitosis

A process where a cell divides to make two identical cells.

Meiosis

A special type of cell division that makes sex cells (like sperm and eggs) with half the usual number of chromosomes.

Prophase

The first stage of cell division when chromosomes become visible and the nuclear membrane starts to break down.

Metaphase

The stage of cell division when chromosomes line up in the middle of the cell.

tRNA

A type of RNA that brings amino acids to the ribosome to build proteins.

Anaphase

The stage of cell division when chromosomes are pulled apart to opposite sides of the cell.

Telophase

The final stage of cell division when two new nuclei form around the separated chromosomes.

Gamete

A cell used for making babies, like sperm or egg.

Somatic Cell

Any body cell that is not a sperm or egg.

Ribosome

A tiny cell part that makes proteins.

Cytokinesis

The final step in cell division when the cell splits into two separate cells.

Nucleus

The control center of a cell that holds the DNA.

Cytoplasm

The jelly-like fluid inside a cell where the cell parts float.

Crossing over

When parts of chromosomes swap places during meiosis, creating genetic variation.

Gene

A section of DNA that gives instructions to make a specific trait or protein.

Phenotype

The physical traits or characteristics you can see in an organism.

Allele

Different versions of the same gene.

Dominant allele

The version of a gene that shows its trait even if only one copy is present.

What are the four phases of Mitosis in order?

prophase, metaphase, anaphase, and telophase

Recessive allele

The version of a gene that only shows its trait if both copies are the same.

Incomplete dominance

When two different alleles blend to make a mix of both traits.

Genotype

The genetic makeup or combination of alleles an organism has.

Homozygous

Having two identical alleles for a gene.

Heterozygous

Having two different alleles for a gene.

Punnett Square

A chart used to predict the possible gene combinations in offspring.

Law of Segregation

The rule that each parent gives one allele for each gene to their offspring.

Independent Assortment

The rule that genes for different traits are passed on separately and randomly.

Monohybrid Cross

A genetic cross that looks at one trait.

Dihybrid Cross

A genetic cross that looks at two traits at the same time.

Carrier

A person who has one copy of a recessive gene but doesn’t show the trait.

Codominance

When both alleles are fully shown together in a trait.

Test Cross

A way to find out an organism’s genotype by crossing it with a recessive organism.

frameshift mutation

A change in DNA where letters are added or removed, shifting the reading frame and changing the whole message.

How is RNA different from DNA?

RNA has a sugar called ribose; DNA has deoxyribose (missing one oxygen).

RNA uses uracil (U) instead of thymine (T).

RNA is usually single-stranded; DNA is double-stranded.

RNA helps make proteins; DNA stores genetic information.

Interphase

The non-dividing portion of the cell cycle where a cell grows, replicates its DNA, and prepares for cell division. It encompasses three distinct phases: G1, S, and G2. 

Prophase

the first stage of mitosis (cell division that produces two identical daughter cells) and meiosis (cell division that produces four unique daughter cells).

Metaphase

the alignment of chromosomes along the metaphase plate, an imaginary line in the middle of the dividing cell.

Anaphase

sister chromatids separate and move to opposite poles of the cell. This process ensures that each daughter cell receives an identical set of chromosomes

Telophase

the final phase of both mitosis and meiosis, where the replicated chromosomes reach opposite poles of the cell, a nuclear membrane forms around each set of chromosomes, and the cell begins to divide

Cytokinesis

Divide the cytoplasm and organelles of the parent cell into two new daughter cells

What are the phases of the cell cycle?

G1, S, G2, M, C

What is the order of mitosis?

Interphase, Prophase, Metaphase, Anaphase, Telophase, and Cytokinesis.

G1

the stage where the cell is preparing to divide.

S

phase where the cell copies all the DNA. stands for DNA synthesis.

G2

it organizes and condenses the genetic material, or starts to condense the genetic material, and prepares to divide`

M

stands for mitosis. This is where the cell actually partitions the two copies of the genetic material into the two daughter cells.

C

divides the nuclei, cytoplasm, organelles and cell membrane into two cells containing roughly equal shares of these cellular components.