Cell Division, Genetics, and Evolution Concepts

Cell division

the process by which a cell divides into two new "daughter" cells

Asexual reproduction

the production of genetically identical offspring from a single-parent

Sexual reproduction

offspring produced inherit some of their genetics from each parent, caused by the fusion of two separate parent cells

Cell cycle

a series of events the cell goes through as they grow and divide

Interphase

the period in between cell divisions. A period of growth that consists of the G1, S, and G2 phases

Mitosis

The first part of the cell division process; this contains 4 major parts: prophase, metaphase, anaphase, and telophase; a process where a single cell divides into two genetically identical daughter cells

Cytokinesis

The second and final stage of cell division; the division of the cytoplasm

Chromosome

tightly packed DNA, found only during cell division. This can be seen with a microscope

Chromatin

a complex of DNA and proteins that condenses DNA into chromosomes

Prophase

the first and longest stage of mitosis; this is where the genetic material inside the nucleus condenses and the duplicated chromosomes become visible, spindle starts to form, and nuclear envelope starts to disappear

Sister Chromatid

two identical copies of a chromatid

Centromere

a structure in a chromosome that holds the two chromatids together

Spindle Apparatus (spindle fibers)

controls the movement and separation of chromosomes during division

Centriole

tiny paired structures; that help in the formation of spindle fibers

Metaphase

the second stage of mitosis, generally the shortest; this is where the centromeres of the duplicated chromosomes line up across the center of the cell on the spindle fibers

Anaphase

the third stage of mitosis; this is where the chromosomes separate and move along spindle fibers to the opposite ends of the cell

Telophase

the final stage of mitosis; this is where the chromosomes, begin to spread out into a tangle of chromatin, and the nuclear envelope starts to appear, the spindle apparatus disappears

Cyclin

a family of proteins that regulate the timing of the cell cycle in eukaryotic cells

Growth Factor

external regulators that stimulate the growth and division of cells

Cancer

a disorder in which body cells lose the ability to control cell growth

Tumor

a mass of cells

G1 phase

cells increase in size and synthesize new proteins and organelles

S phase

new DNA is created when the chromosomes are replicated

G2 phase

many of the organelles and molecules required for cell division are produced

Functions of mitosis

The two main functions of mitosis are growth and repair

Regulation of cell cycle

The cell cycle is controlled by regulatory proteins both inside and outside the cell; these proteins are cyclins

Cancer cell characteristics

Cancer cells do not respond to the signals that regulate the growth of most cells. As a result, the cells divide uncontrollably.

Binary Fission

A single parent cell doubles its DNA, then divides into 2 cells. Usually occurs in Bactris.

Fragmentation

The organism breaks into 2 or more fragments that develop into a new individual.

Budding

Small growth on the surface of a parent breaks off, resulting in the formation of 2 individuals.

Parthenogenesis

An embryo develops from an unfertilized cell.

Diploid Cell

A diploid cell contains 2 complete sets of homologous pairs.

Haploid Cell

A haploid cell contains 1 set of chromosomes, which is half of a diploid cell.

Diploid Cell Symbol

2n=46

Haploid Cell Symbol

n=23

Chromosomes

Strands of proteins and DNA inside a nucleus that carry genetic information, genes.

Human Chromosomes

46 chromosomes; you need one gamete from each parent, which contains 23 chromosomes each.

Characteristics of Homologous Chromosomes

Same length, same location of centromere, carry genes that control the same inherited traits, located in similar positions.

Meiosis

The process by which the number of chromosomes per cell is cut in half by the separation of homologous chromosomes in a diploid cell.

Meiosis 1: Interphase 1

Chromosomes replicate, cell grows, gets ready to divide, makes proteins, and other resources needed.

Meiosis 1: Prophase 1

Homologous chromosomes pair up and become tetrads, go through crossing over, chromatin condenses into chromosomes, spindle fibers start to form, nuclear envelope disappears.

Meiosis 1: Metaphase 1

The tetrads line up in the middle of the cell, and the homologous chromosomes are arranged for genetic variation.

Meiosis 1: Anaphase 1

The spindle fibers pull the chromosomes to opposite sides of the cell.

Meiosis 1: Telophase 1

A nuclear envelope forms, spindle fibers disappear, chromosomes decondense into chromatin, and the cell undergoes cytokinesis.

Results of Telophase 1

Two haploid cells that have 23 chromosomes each.

Meiosis 2: Interphase 2

Same as prophase 1 except no crossing over occurs, and are plain chromosomes, not tetrads.

Meiosis 2: Telophase 2

The nuclear envelope appears, spindle fibers disappear, cell goes through cytokinesis.

Results of Telophase 2

4 haploid cells that are genetically diverse.

Gametes

The reproductive cells; in male animals the gamete is called sperm, in female animals the gamete is called egg.

Fertilization

The fusion of male and female gametes, generating new combinations of genes.

Differences between Mitosis and Meiosis

In mitosis, you get 2 sets of chromosomes (46). In meiosis, you get one set of chromosomes (23).

Diploid

A cell that contains two complete sets of chromosomes, represented as 2n=46.

Haploid

A cell that contains one complete set of chromosomes, represented as n=23.

Mitosis Formula

(2nx2) /2

Meiosis Formula

(2nx2) /4

Gene

Factors that are passed from parent to offspring.

Gamete

The reproductive, or sex cells.

Heredity

A biological process where a parent passes certain genes onto their offspring.

Genetics

The key to understanding what makes each organism unique.

Trait

A specific characteristic, such as seed color or plant height, of an individual.

Hybrid

The offspring of crosses between parents with different traits (heterozygous).

Pure Trait

An individual possessing two identical alleles of a gene for a specific characteristic, meaning they will always express that trait (Homozygous).

Allele

The different forms of genes.

Dominant Alleles

Show their effect with only one copy of the allele.

Recessive Alleles

Show their effect with two copies of the allele.

Phenotype

Physical traits, meaning 'to show'.

Genotype

Genetic makeup, meaning 'race, kind'.

Homozygous

Organisms that have two identical alleles for a specific gene.

Heterozygous

Organisms that have two different alleles for the same gene.

Punnet Square

A simple diagram that helps to predict the genetic cross.

Gregor Mendel

Father of Modern Genetics, an Australian Monk.

Monohybrid Cross

A cross that shows only one trait.

Dihybrid Cross

A cross that shows 2 traits.

Frederick Griffith

Scientist who isolated 2 similar bacteria from mice and discovered bacterial transformation.

Oswald Avery

Discovered that DNA stores and transmits genetic information from one generation of bacteria to the next.

Alfred Hershey and Martha Chase

Confirmed that DNA was the genetic material found in genes through their experiment with bacteriophages.

Erwin Chargaff

Discovered that the base pairs A and T are equal to each other, and so are C and G, known as Chargaff's rule.

Rosalind Franklin

Provided crucial clues about the structure of DNA through her X-ray pattern.

Maurice Wilkins

Uncovered the structure of DNA and showed the first crystalline symmetrical patterns of DNA.

James Watson and Francis Crick

Built a model that explained the specific structure and properties of DNA, discovering the double helix in 1953.

Deoxyribonucleic Acid (DNA)

A molecule that carries genetic information.

Monomer

A building block molecule that can link with other molecules to form a larger molecule.

Nucleotide

The monomer of nucleic acids, consisting of a phosphate, a sugar, and a nitrogen base.

Amino acids

The building blocks of proteins; there are 20 types of amino acids.

Phosphate

A component of a nucleotide that is part of the backbone of DNA and RNA.

Carbon Sugar (Deoxyribose)

A sugar molecule in DNA that is part of the nucleotide structure.

Nitrogen Base

A component of a nucleotide that can be adenine, thymine, cytosine, or guanine.

Pentose Sugar

A five-carbon sugar that can be either deoxyribose or ribose.

Double strand of nucleotides

The structure of DNA, consisting of two strands held together by base pairs.

Base Pair Rule

Adenine can bond only with Thymine and Cytosine can only bond with Guanine.

Adenine (A)

A nitrogenous base that pairs with Thymine in DNA.

Thymine (T)

A nitrogenous base that pairs with Adenine in DNA.

Cytosine (C)

A nitrogenous base that pairs with Guanine in DNA.

Guanine (G)

A nitrogenous base that pairs with Cytosine in DNA.

Purines

Nitrogenous bases with two rings of carbon and nitrogen atoms; includes Adenine and Guanine.

Pyrimidines

Nitrogenous bases with one ring of carbon and nitrogen atoms; includes Thymine, Uracil, and Cytosine.

Complementary Strand of DNA

A strand of DNA that pairs with a given strand according to base pairing rules.

DNA replication

The process by which DNA makes a copy of itself.

Topoisomerase

An enzyme that helps to unwind the DNA double helix in DNA replication.

DNA Helicase

An enzyme that helps to unzip the DNA strands to prepare them for replication.