Bio Final

Asexual Reproduction

1 cell divides to become 2 cells (cells are genetically identical to the parent cell)

Binary Fission

Asexual reproduction in bacteria

Budding

Asexual reproduction in organism in which a new (smaller) organism grows out of an existing organism

Clone

A cell (or organism) that is genetically identical to another

Cell Cycle

A series of stages that a cell goes through during its life cycle (interphase, mitosis & cytokinesis)

Interphase

1st - the cell grows, makes more organelles & copies all the DNA (replication)

Mitosis

2nd - the two copies of DNA are split apart (prophase, metaphase, anaphase & telophase) into two nuclei.

Cytokinesis

3rd part of the cell cycle - the cytoplasm of the cell divides & creates two distinct cells

Cleavage Furrow

Indentation formed by an animal cell's cell membrane pinching in during cytokinesis.

Cell Plate

The structure that divides a single plant cell into two smaller cells during cytokinesis (becomes the cell wall).

Chromatin

Unwound DNA (it is long and thin)

Chromosome

Tightly wound up DNA seen during mitosis; contains an organism's genetic information (genes)... each human body cell contains 46 chromosomes.

Sister Chromatid

The two halves of an X shaped chromosome (they are identical to one another thanks to replication)

Somatic Cell

A body or non-reproductive cell (has 2 sets of chromosomes)... in humans these cells have 46 chromosomes.

Sexual Reproduction

Reproduction in which 2 cells unite to form a single cell with a new combination of genetic information.

Gamete

A reproductive cell such as egg or sperm. They contain only 1 set of DNA

Meiosis

The process that makes reproductive cells (i.e. eggs or sperm)

Spermatogenesis

Meiosis that occurs in the testes - making of sperm (1 cell divides to become 4 sperm)

Oogenesis

Meiosis that occurs in the ovaries - making of egg (1 cell becomes 1 egg + 3 polar bodies)

Polar Body

A cell made by oogenesis; it does not get used for reproduction (the body discards it).

Homologous Pair

A pair of chromosomes that have the same kinds of genes on them (one is from mom & the other is from dad).

Haploid

A cell with only 1 set of chromosomes (1N) - Ex: egg or sperm

Diploid

A cell with 2 sets of chromosomes (2N) - Ex: skin, muscle, nerve cells.

Crossing Over

The swapping or exchanging of genes between homologous chromosomes (source of genetic variation)

Zygote

A fertilized egg (contains two sets of chromosomes - 1 from sperm + 1 from egg)

Nondisjunction

Failure of chromosomes to separate during meiosis. This is a major mistake that causes gametes to have too many or to be missing chromosomes

Karyotype

A picture of chromosomes that have been organized by size, banding pattern & type. These are often used to identify chromosomal mistakes (such as those caused by Down Syndrome).

Autosomes

All of the non-sex chromosomes (in a normal human there are 44)

Sex chromosomes

The pair of chromosomes that determine gender (XX \= girl XY \= boy)

Monosomy

When a single chromosome is missing (normally there should be a pair of each chromosome).

Trisomy

When a cell has an extra chromosome (normally there should be a pair of each chromosome... Ex: Trisomy

21... there are 3 21» chromosomes).

DNA Fingerprinting

Creating a series of bands from an individual's DNA. Forms a picture that looks like a barcode.

Restriction Enzyme

Enzvmes that cut DNA at specific places (sequences of Gs, Cs, As and Ts)

Gel Electrophoresis

Cut up DNA or proteins are placed into a gel and are separated based upon their size (using an electrical charge).

Biotechnology

The science of modifying living organisms or things they make to improve human health and their environment.

Genomics

The study of organisms and all the genes in their genome

Human Genome Project

The task of reading the billions of Gs, Cs, As and Ts in the human DNA. Then trying to interpret what the series of letters means (identifying the location of specific genes).

Gene Therapy

Inserting normal (healthy) genes into the DNA of someone who has a defective gene. Purpose is to cure disorders. Still in the experimental phase.

Transformation

Creating new DNA by combining DNA from two different sources (the new DNA is called recombinant DNA)

Transgenic Organisms

An organism that contains DNA from a different species.

Plasmid

A circular piece of DNA found in a bacteria cell.

Genetically Modified Organisms (GMO)

An organism whose DNA has been changed (often by inserting foreign DNA)

Stem Cells

Cells that the body makes that are able to divide and form any type of cell (skin, muscle, bone nerve, etc.)

Stem cell research

Using stem cells to attempt to cure disease or re-grow tissue (and one day maybe even organs) to replace ones that have worn out.

Genetics

The study of how traits are inherited from one generation to the next.

Gregor Mendel

The man that is credited with discovering basic patterns of inheritance in pea plants in the late 1800s.

Gene

A piece of a chromosome which contains instructions for a particular characteristic or trait (tells how to make a protein)

Trait

A characteristic that is controlled by your genes.

Allele

The different forms of a gene (represented by a single letter or symbol)

Dominant

An allele that is expressed, even when paired with a different allele. It is represented by a capital letter.

Recessive

An allele that is hidden or masked if paired with a different allele. It is represented by a lowercase letter.

Genotype

The genetic makeup of a trait, represented by a pair of alleles (Ex. Rr or rr)

Phenotype

The physical expression of a trait, represented by a word (Ex: Red or white)

Homozygous

A pair of alleles that are the same (Ex. RR or rr). Also known as pure, purebred, or true breeding.

Heterozygous

A pair of alleles that are different (Ex: Rr). Also known as a hybrid.

Punnet Square

A tool used to determine the possible offspring of a cross between two parents

Corssing

The term used to describe when two organisms mate or breed.

Offspring

Another term for child or children

P1 Generation

When looking at several generations, these are the parents (the first ones to be mated or crossed). In Mendel's experiments - he crossed two purebred parents with differing traits [i.e. pure tall (IT) x pure short (L

F1 Generation

The offspring of the P1 generation. In Mendel's experiments these were always hybrids (Tt).

F2 Generation

The offspring of the F1 generation.

Probability

The likelihood that an event will occur

Monohybrid Cross

A cross that involves one trait (Tall × short ) '

Dihybrid Cross

A cross that involves two traits (Tall & red × short & white)

Test Cross

A way of finding out the genetic makeup of a parent that shows a dominant trait. They are mated with an organism that is homozygous recessive. Looking at their offspring helps determine genotype of the parent with the dominant trait.

Complete Dominance

In a heterozygote - the dominant allele is able to completely cover or mask the recessive allele. Example: R \= red r \= white Rr \= RED

Incomplete Dominance

In a heterozygote - the dominant allele mixes with the recessive allele and forms a new phenotype (neither allele shows). Example: R \= red r \= white Rr \= PINK

Codominance

In a heterozygote - two different alleles are dominant and BOTH show at the same time. Example: HR\= red HW \= white HR HW \= RED and WHITE

Multiple Alleles

When a single gene has more than two possible alleles. Blood type is an example because there are 3 different alleles: IA B and i

Polygenic Traits

A trait that is controlled by 3 or more genes. These traits have a wide variety of phenotypes; Examples include: height, hair color, eye color, skin color

Sex-Linked Traits

Traits that are controlled by genes on the sex chromosomes.

Pedigrees

A chart that shows the inheritance of a trait over several generations. Affected individuals are shaded in; carriers (heterozygotes) are shaded in half way. Circles \= females

squares \= males

Carrier

Term used to describe individuals that are heterozygous for a recessive disorder. They are healthy, but may pass the allele for the disease down to their children.

Autosomal Disorders

Disorders that are caused by genes on the non-sex chromosomes. These tend to affect males and females equally.

Sickle Cell

A mutation (in a protein called hemoglobin) that affects the shape of red blood cells; People who suffer from sickle cell inherit the sickle allele from both parents. • Carriers (heterozygotes) are protected from Malaria (common around equator)

Cystic Fibrosis

A mutation that causes mucous in the body to be thick; major problems with the lungs. Since it is recessive, sufferers must inherit the allele from both parents to be sick.

Huntington's Disease

A disorder caused by a dominant allele; it causes the nervous system to fail beginning between 30-40 years old. • Since it is dominant, only need to inherit it from one parent to have the disorder.

PKU

A disorder that prevents the body from breaking down an amino acid called phenylalanine. Accumulation over the long term will cause mental retardation. Avoidable as long as person does not eat foods with phenylalanine.

Sex Linked Disorders

Disorders that are caused by genes on the sex chromosomes. These tend to affect males more often than females.

Color Blindness

A recessive disorder found on the X chromosome. Those that suffer from it are not able to distinguish between certain colors (red-green colorblindness is the most common form).

Hemophilia

A recessive disorder found on the X chromosome. Those that suffer from it are not able to clot (which means they can easily bleed to death).

Evolution

A genetic change of a species over time.

Mutations

Mistakes or changes in DNA (this is a major source of change that fuels evolution)

Adaptation

A genetic change that increases an organism's chance of survival

Acquired Traits

A flawed theory that states that features that are gained in an organism's lifetime and is then able to be passed down to their children (this theory is NOT supported today)

Natural Selection

When the environment favors a trait (an organism with that trait is more likely to survive)

Descent with Modification

Current species are just changed versions of organisms of the past.

Modification by Natural Selection

It is the environment that determines which organism has favorable traits (in other words who survives.

Fitness

A measure of an organism's ability to produce offspring (to pass their genes down to the next generation)

Survival of the Fittest

Organisms best adapted to their environment will produce the most offspring (a.k.a. natural selection)

Divergent Evolution

When two or more species form from one common ancestor and become more different over time ... often results in homologous structures. Ex: Differences seen in the forelimbs of all mammals. Whale fin, human arm & bat wing all have the same bones, but their design/function has changed over time.

Convergent Evolution

When two or more species begin to look alike (usually adapting to the same environment), even though their ancestors did not... often results in analogous structures. Ex: Dolphin and Shark (both adapted to swim though they come from different ancestors)

Vestigial Structures

Structures that were once used in an organism's ancestors but no longer serve a useful function even though it is still present in the organism's body. Ex: Human appendix and tailbone

Coevolution

When two different, unrelated species change over time due to the presence of one another.

Speciation

The formation of a new species from an existing species.

Embryology

Examining embryo development to determine how closely related two species are.

Comparison of Macromolecules

Comparing an organism's DNA and/or proteins to determine how closely related two species are.

Selective Breeding or Artificial Selection

Humans determine which organisms get to mate or reproduce based upon traits of their choosing. This process can change a species over time.