Honors Biology Exam

Mitosis

cell division in which all parts inside the cell are copied and then the cell splits into 2 new cells

Mitosis is also called

the cell cycle

Chromosomes

structures found in the nucleus that carry DNA

Genes

parts of the chromosomes that carry genetic information

Somatic cells

body cells

Sex cells

egg cells in females and sperm cells in males are referred to as gametes ( germ cells)

Interphase

Occurs before mitosis

What is Interphase divided into?

G1, S, G2

During G1 phase

the cell grows rapidly

During S phase

DNA copies itself in a process called replication

During G2 phase

all the organelles in the cell are replicating and the cell is growing

The cell spends how much time in Interphase?

90%, Interphase is the longest part of the cell cycle

Mitosis: Prophase

the first stage of mitosis in which the chromatin material forms chromosomes.

Mitosis: Metaphase

chromosomes line up in the middle of the cell

Mitosis: Anaphase

chromosomes separate and move to opposite ends of the cell, each containing a piece of the centromere.

Mitosis: Telophase

The nuclei reappear and the chromosomes become thin chromatin material

Mitosis: Cytokinesis

in animal cells, the cytoplasm splits and 2 new cells are formed

Meiosis

the production of egg and sperm; cell division takes place two times; 4 new cells are created

Interphase

The cell goes through G1, S, and G2 (meiosis)

Prophase I

The homologous chromosomes, which carry the same information, find each other (meiosis)

Metaphase I

the homologous chromosomes line up in the middle of the cell. (meiosis)

What can occur during Metaphase I?

Genetic variations when the tetrads are formed.

Inversion

a mutation in which a piece of a chromosome (chromatid) breaks off and reattaches at another place on the chromosome (chromatid). This causes the order of genes to be "rearranged."

Deletion

A piece of the chromosome breaks off and is lost

Nondisjuction

tetrads or chromosomes fail to split

Anaphase I

the homologous chromosomes split and move to opposite sides of the cell. (meiosis)

Telophase I

the chromosomes move to opposite sides of the cell, the new nucleus forms, and new nucleolus forms (meiosis)

Cytokinesis I

the cell splits into 2 new cells. Each new cell has fully formed chromosomes (meiosis)

Interphase II

Almost the same as interphase 1, but there is no DNA replication and the chromosomes do not replicate. Two cells go through this process (meiosis)

Prophase II

The chromosomes have already formed. The cell gets ready for Metaphase II. (meiosis)

Metaphase II

the chromosomes line up in the middle of the cell (meiosis)

Anaphase II

the chromosomes split into single strands and begin moving to the opposite sides of the cell (meiosis)

Telophase II

Single chromosomes are in newly forming nuclei and the cells are beginning to split. (meiosis)

Cytokinesis II

Newly formed cells have half the number of chromosomes that the original cell had. (meiosis)

Genetics

the study of heredity

Gregor Mendel

Father of genetics, experimented on pea plants to examine different traits

Characteristics

traits

Monomers of DNA

nucleotides

What are nucleotides made up of?

Nitrogen base, ribose sugar, and phosphate group

Histone

twisted DNA strands wrap around a protein.

What does a histone form?

nucleosome

DNA forms what?

chromatin material which forms chromosomes. Chromosomes are made of both DNA and protein

Chromosomes contain what?

genes

How many chromosomes do humans have?

46 (23 pairs)

Punnett square

diagram showing the gene combinations that might result from a genetic cross

Dominant gene

A gene that is expressed in the offspring whenever it is present

Recessive gene

Gene that is hidden when the dominant gene is present

Homozygous

An organism that has two identical alleles for a trait whether dominant or recessive (ex: TT, or tt)

Heterozygous

An organism that has two different alleles for a trait. Takes on the dominant trait, but carries the recessive trait (ex: Tt)

Genotype

genetic makeup of an organism

Phenotype

an organism's physical appearance, or visible traits

When alleles are homozygous they are...

purebred

When alleles are heterozygous they are...

hybrid

Incomplete dominance

one allele is not completely dominant over another allele (ex: red flower + white flower \= pink flower)

Codominance

both alleles for a gene are expressed (ex: a black cat with white spots)

Sex-linked traits

traits controlled by genes located on the X chromosome (ex: color blindness)

Pedigree

A chart or "family tree" that tracks which members of a family have a particular trait

Protein Synthesis

the formation of proteins by using information contained in DNA and carried by mRNA

Fred Griffith

He compared the effects of two kinds of bacteria on mice. His study suggested that DNA was probably the cell's genetic material.

Hershey and Chase

experiments on viruses and proved that DNA was the cell's genetic material

Four bases of DNA

Adenine, Thymine, Guanine, Cytosine

Chargaff

responsible for discovering the base pairing rules for DNA.

Chargaff's Rule

Adenine binds to Thymine and Cytosine binds to Guanine

What substitutes for thymine in RNA?

Uracil

Transcription

making mRNA (messenger RNA)

DNA replication

The process in which DNA makes a duplicate copy of itself.

Translation

Process by which mRNA is decoded and a protein is produced

RNA

is made of nucleotides and is one strand. It can leave the nucleus.

3 types of RNA

mRNA, tRNA, rRNA (messenger, transfer, ribosome)

Ribosomes

Makes proteins

Codons

The three-base sequence of nucleotides in mRNA

Anti-codons

three nucleotide sequence that is complementary to the codon on the mRNA, located in tRNA

Start codons

signals the start of translation

Stop codons

signal the end of an amino acid chain

Amino acids

monomers of proteins

Peptide bonds

Bonds between amino acids

Proteins

Chains of amino acids

Charles Darwin

English natural scientist who formulated a theory of evolution by natural selection. Visited Galapagos Island

Lamarck

Proposed theory that organisms can change in a short period of time

Character Displacement

Species evolve non-overlapping traits to avoid competition

Survival of the Fittest

Process by which individuals that are better suited to their environment survive and reproduce most successfully; also called natural selection

Evolution

The gradual change in a species over time

Species

A group of similar organisms that can breed and produce fertile offspring.

Population

A group of individuals that belong to the same species and live in the same area

Community

All the different populations that live together in an area

Habitat

Place where an organism lives

Niche

An organism's role in their environment

intraspecific competition

competition between members of the same species

interspecific competition

competition between members of different species

resource partitioning

When species divide resources to avoid competition for them

homologous structures

structures that look similar but are used for different purposes. They appear to have a similar ancestor

analogus structures

structures that are similar in function but do not have a similar ancestor

Vestigial structures

structures that may have had a function at one point but no longer do (ex: appendix, wisdom teeth, tailbone)

Stabilizing natural selection

Favors the average population

Directional natural selection

Favors one extreme of the population

Disruptional natural selection

Average population dies out, favors both extremes of the population, loses the majority

Ecosystem

Different communities and their physical surroundings all together

Divergent evolution

organisms change into new species to adapt to their environment

Covergent evolution

different species living in the same area become more alike

Mimicry

an organism mimics another organism