Bio Exam #2

Cancer cell differences

Divide when they shouldn’t, invade surrounding tissue, move to other location

Cancer

Unregulated cell division

Tumor

mass of cells with no function

Benign tumor

Doesn’t affect surrounding tissue

Malignant tumor (cancerous)

Invades surrounding tissues

Metastasis

Cell breaks away from malignant tumor and starts a new cancer at another location

How do metastatic cells travel?

Circulatory system or lymphatic system

Cancer risk factors

Tobacco use, carcinogens, alcohol consumption, high fat/low fiber diet, lack of exercise, increasing age

Asexual reproduction

One parent, offspring are genetically identical to parent

Sexual reproduction

Gametes are combined from two parents, offspring are genetically different from one another and parents

Chromosome

Long strand of DNA tightly wrapped around proteins

Centromere

Duplicated chromosomes are held together here

Sister chromatids

Duplicated DNA held together at the centromere

DNA replication

When DNA is replicated to prepare for cell division

Karyotype

A type of diagram showing chromosomes of a person (chromosomes are visible during mitosis)

DNA Polymerase

Enzyme that replicated DNA forming covalent bonds between nucleotides on the backbone of a new strand and hydrogen bonds between nucleotides on different DNA strands

Semiconservative replication

When two identical daughter molecules are created, each with a part of the original

Cell cycle

The lifecycle of the cell

Interphase

Phase where DNA replicates

Mitosis

Phase where copied chromosomes are moved into daughter cells

Cytokinesis

Phase where cell splits into two different daughter cells

Phases of Interphase

G1: cell growth, organelles duplicate

S: DNA replicates

G2: cell makes proteins needed to complete mitosis

Phases of Mitosis

Prophase, Metaphase, Anaphase, Telophase

Cytokinesis in plants and animals

Plants: cell wall forms between cells, from cellulose

Animals: proteins pinch original cell into two new cells

Checkpoints

Points during interphase and mitosis where proteins survey condition of cell, must pass to proceed with cell division

G1 checkpoint

Are growth factors present, is DNA damaged, is cell large enough and has nutrients

G2 checkpoint

Did DNA replicate properly

Metaphase checkpoint

Have chromosomes attached properly to microtubles

Proto-oncogenes

Genes that produce proteins to control the cell cycle

Mutation

Change in the sequence of DNA

Oncogenes

Mutated proto-oncogenes

Tumor suppressor genes

Genes for proteins that will stop cell division if something isn’t right

Angiogenesis

When tumors get their own blood supply

Loss of contact inhibition

Cells pile up on each other

Loss of anchorage dependence

Allows cancer cells to move to another location

Immortalized

Cells that have no fixed number of cell divisions

Multiple hit model

Cancer development requires multiple mutations

Meiosis differences

Cell division in gonads to produce gametes, reduces number of chromosomes in each cell, creates haploids instead of diploids

Phases of Meiosis

Meiosis I and Meiosis II

Meiosis I

Separates duplicated homologous chromosomes into two cells (may have crossing over), resulting cells are haploid

Meiosis II

Separates sister chromatids of a homologous pair into individual cells, one chromosome per cell, results in gamete

Crossing over

Exchange of equivalent portions of chromosomes between members of homologous pair (occurs in prophase I

Random alignment

The ways that different pairs of chromosomes align and get separated during meiosis I is random

Nondisjunction

Failure of homologues to separate normally during meiosis

Trisomy

Gamete with one too many chromosome

Monosomy

Gamete with one too few chromosome

Gene

Short region of DNA molecule that code a certain protein

Allele

Specific version of a gene

Autosome

The main chromosomes (1-22)

Sex chromosomes

X or Y chromosome

Diploid

Two copies of each chromosome (somatic cells)

Haploid

Only one copy of each chromosome (reproductive cells)

Phenotype

Expression of a genetic trait

Genotype

Genetic make up (genes on the chromosome)

Homozygote

Same two alleles (AA or aa)

Heterozygote

Two different alleles (Aa)

Johann “Gregor” Mendel

Father of genetics

Ways variation is created

Mutation, random alignment, crossing over, fertilization

Independent Assortment

Each homologous chromosome is separated without relation to the other

Linkage

Two genes on the same chromosome (not independently assorted, segregate together

Polygenic Traits

Traits determined by two or more genes

Dihybrid crosses

Crosses involving two traits

Incomplete dominance

Two dominant allele copies needed for full phenotype, heterozygote phenotype is intermediate to the homozygotes

Codominance

Neither allele is dominant to the other, heterozygote shows both traits at once (no blending)

Multiple alleleism

When there are multiple alleles for one gene

Sex-linked genes

Genes located on the sex chromosomes

Pedigree

Family tree that shows the inheritance of traits over several generations

DNA Fingerprinting

Equivalent to human barcode or fingerprint and helps with identification of individuals

DNA fingerprinting steps

1. DNA isolated from tissue sample

2. DNA cut into fragments with enzymes

3. Fragments separated on basis of size and visualized (each is unique)

PCR (Polymerase Chain Reaction)

DNA mixed with nucleotides, primers, Taq polymerase, and is heated, which splits DNA into complementary strands. Taq polymerase then builds a new complementary strand and process repeats

Overhang

DNA is cut with “sticky ends”, think cut diagonally but evenly

Blunt ends

DNA is cut straight across

Gel electrophoresis

DNA fragments are separated based on size, electric current is applied to agarose gel and the smaller fragments will run faster through the gel

Protein synthesis

Using instructions on a gene to create proteins

RNA (Ribonucleic Acid)

Single strand with nucleotides composed of ribose and four nitrogenous bases (same as DNA but U replaces T)

Transcription

Making RNA in the nucleus, produces messenger RNA (mRNA)

Translation

Making proteins in the cytoplasm

RNA polymerase

Enzyme that zips down the gene and matches RNA nucleotides with DNA nucleotides

Promoter

Region where the RNA polymerase knows to start

Translation requirements

mRNA, rRNA, tRNA

Ribosomes

Made of rRNA and is made of a large subunit and a small subunit

Transfer RNA (tRNA)

Carries amino acids and matches anticodon with codon on mRNA, in cytoplasm

Process of Translation

Ribosomes attach to mRNA at promoter region, ribosomes allow tRNA to match anticodons to mRNA codons, the two tRNA’s next to each other form a bond between their amino acids

Stop Codon

Sequence of three base pairs that indicate the end of the RNA to be translated

Outcomes of mutation to protein

1. No change in protein

2. Non-functional protein

3. Different protein

Substitution

Changes one amino acid

Insertion or deletion

Causes frameshift

Regulating Gene Expression

Turning a gene or a set of genes on or off

Genetic Engineering

Altering hereditary traits by molecular biological techniques

rBGH

Growth hormones that increase body size and milk production in cows

Restriction enzymes

Enzymes used in bacteria as a defense. Cuts DNA at specific sequences

Plasmid

Small circular piece of bacterial DNA that exists separate from bacterial chromosome, can ferry a gene into a cell

Recombinant

Material that has been genetically engineered

Steps in creating rBGH

1. Remove gene from cow chromosome

2. Insert BGH gene into bacterial plasmid

3. Insert recombinant plasmid into bacterial cell, which creates millions of copies of rBGH gene and protein, which is then put into the cows

Artificial selection

Using selective breeding to change the characteristics of a population

Transgenic organism

Also called Genetically Modified Organism (GMO), the result of incorporating a gene from one organism to the genome of another

Benefits of GMO foods

Increase shelf life, yield, or nutritional value

Stem cells

Undifferentiated cells, in embryo can grow to many different cells and tissues, in adults function as a repair system

Gene Therapy

Replacement of defective genes with functional genes

Germ line gene therapy

Embryonic treatment where embryo or every cell is supplied with a functional version of the defective gene