AN-1511 Chapter 3: Genetics

DNA cloning

What is the technique that allows scientists to make multiple copies of a DNA segment?

A sugar molecule attached to a phosphate group and a nitrogen-containing base

What is a nucleotide and what is it composed of?

One genetic locus

A Mendelian trait could be influenced by alleles at how many loci?

Mutations, Gene Flow, Genetic Drift (Founder and Bottleneck)

What are the non-Darwinian mechanisms of evolution?

Rosalind Franklin

Who discovered the structure of DNA from taking Xray photos of the molecule?

Adenine, Thymine, Guanine, Cytosine

What are the four bases found in DNA?

nucleus

DNA is the fundamental component of what part of the human cell?

Found in the mitochondria, inherited from the maternal line, has about 37 genes that code for proteins

What is mitochondrial DNA, where does it come from and what does it do?

Enzymes are proteins that initiate and direct chemical reactions in the body

What are enzymes and what do they do?

Genes come in pairs, inherited from distinct units (one from each parent)

What principles of genetic heredity did Gregor Mendel identify?

3 tall plants for every short plant 3:1

What pattern in the expression of traits did Mendel’s research into pea plant hybrids reveal?

Dominant/ Recessive relationship, homozygous or heterozygous

What are the possible relationships between alleles?

Co-dominance

when both alleles are expressed separately

Incomplete dominance

when alleles allow blending with the recessive allele color

Change in the number or structure of chromosomes

What aspects of chromosomes do mutations change?

Creates a permanent change to DNA sequence, which leads to evolution

How do mutations affect genetic variability?

Protein synthesis is associated with

mRNA

Chromosomes in nucleus

Within what part of the cell are chromosomes contained?

Telophase

What process causes the daughter cells to contain the same amount of DNA as the original cell after mitosis has occurred?

An international effort aimed at sequencing and mapping the entire human genome.

What is the primary goal Human Genome Project?

Sex chromosomes

what the X and Y chromosomes are called

99.9% with other humans, 98% with chimps, 50% with bananas, 33% with yeast

What are some examples of the shared % of DNA in humans and other organisms?

Cells in the body that are not involved with reproduction

What are the characteristics of somatic cells?

Skin color, eye color, hair color, height

What are some examples of polygenic traits?

Regulatory proteins, enzymes, hemoglobin

What kinds of proteins are there?

We are made of proteins, most hormones are proteins produced in specialized cells, regulatory proteins bind DNA switching genes on and off, and enzymes initiate and direct chemical reactions like lactase

Name four facts about proteins

Sickle-cell anemia, Tay-Sachs disease

Which Mendelian traits are genetically-caused diseases?

genetics

The study of gene structure and

action and of the patterns of inheritance

of traits from parent to offspring. Genetic

mechanisms are the underlying foundation

for evolutionary change.

nucleus

A structure (organelle) found in

all eukaryotic cells. The nucleus contains

chromosomes (nuclear DNA).

deoxyribonucleic acid (DNA)

The

double-stranded molecule that contains

the genetic code. DNA is a main compo-

nent of chromosomes.

ribonucleic acid (RNA)

A molecule similar

in structure to DNA. Three different single-

stranded forms of RNA are essential to

protein synthesis.

cytoplasm

The portion of the cell con-

tained within the cell membrane, excluding

the nucleus. The cytoplasm consists of a

semifluid material and contains numerous

structures involved with cell function.

proteins

Three-dimensional molecules

that serve a wide variety of functions

through their ability to bind to other

molecules.

protein synthesis

The assembly of chains

of amino acids into functional protein mol-

ecules. The process is directed by DNA.

somatic cells

Basically, all the cells in

the body except those involved with

reproduction.

gametes

Reproductive cells (eggs and

sperm in animals) developed from precur-

sor cells in ovaries and testes.

zygote

A cell formed by the union of an

egg and a sperm cell. It contains the full

complement of chromosomes (in humans,

46) and has the potential to develop into an

entire organism.

molecule

A structure made up of two or

more atoms. Molecules can combine with

other molecules to form more complex

structures.

nucleotides

Basic units of the DNA mol-

ecule, composed of a sugar, a phosphate

unit, and one of four DNA bases.

hemoglobin

A protein molecule that

occurs in red blood cells and binds to oxy-

gen molecules.

hormones

Substances (usually proteins)

that are produced by specialized cells and

travel to other parts of the body, where

they influence chemical reactions and regu-

late various cellular functions.

amino acids

Small molecules that are the

components of proteins.

gene

A sequence of DNA bases that speci-

fies the order of amino acids in an entire

protein or, in many cases, a portion of a

protein, or any functional product. A gene

may be made up of hundreds or thousands

of DNA bases.

mutation

A change in DNA. The term

can refer to changes in DNA bases as well

as changes in chromosome number or

structure.

regulatory genes

Genes that code for the

production of proteins that can bind to

DNA and modify the action of genes. Many

are active only during certain stages of

development.

chromosomes

Discrete structures, com-

posed of DNA and protein, found only in

the nuclei of cells. Chromosomes are visible

only under magnification during certain

stages of cell division.

centromere

The constricted portion of

a chromosome. After replication, the two

strands of a double-stranded chromosome

are joined at the centromere.

mitosis

Simple cell division; the process by

which somatic cells divide to produce two

identical daughter cells.

meiosis

Cell division in specialized cells

in ovaries and testes. Meiosis involves

two divisions and results in four daughter

cells, each containing only half the original

number of chromosomes. These cells can

develop into gametes.

recombination

The exchange of DNA

between paired chromosomes during meio-

sis; also called crossing over.

clones

A clone is an organism that is

genetically identical to another organism.

In addition to entire organisms, the term

may also be used to refer to genetically

identical DNA segments and molecules.

hybrids

Offspring of mixed ancestry;

heterozygotes.

principle of segregation

Genes (alleles)

occur in pairs (because chromosomes occur

in pairs). During gamete production, the

members of each gene pair separate, so

that each gamete contains one member of

each pair. During fertilization, the full num-

ber of chromosomes is restored, and mem-

bers of gene pairs (alleles) are reunited.

recessive

Describing a trait that is not

expressed in heterozygotes; also refers to

the allele that governs the trait. For a reces-

sive allele to be expressed, there must be

two copies of the allele (i.e., the individual

must be homozygous).

dominant

Describing a trait governed

by an allele that can be expressed in the

presence of another, different allele (i.e.,

in heterozygotes). Dominant alleles pre-

vent the expression of recessive alleles in

heterozygotes. (Note: This is the definition

of complete dominance.)

locus

The position on a chromosome where a given gene

occurs. The term is sometimes used inter-

changeably with gene.

alleles

Alternate forms of a gene. Alleles

occur at the same locus on paired chro-

mosomes and thus govern the same trait.

However, because they are different, their

action may result in different expressions

of that trait. The term allele is often used

synonymously with gene.

homozygous

Having the same allele at the

same locus on both members of a chromo-

some pair.

heterozygous

Having different alleles at

the same locus on members of a chromo-

some pair.

genotype

The genetic makeup of an indi-

vidual. Genotype can refer to an organism’s

entire genetic makeup or to the alleles at a

particular locus.

phenotypes

The observable or detectable

physical characteristics of an organism; the

detectable expressions of genotypes.

principle of independent assortment

The distribution of one pair of alleles into gam-

etes does not influence the distribution of

another pair. The genes controlling differ-

ent traits are inherited independently of

one another.

antigens

Large molecules found on the

surface of cells. Several different loci gov-

erning antigens on red and white blood

cells are known. (Foreign antigens provoke

an immune response in individuals.)

polygenic

Referring to traits that are

influenced by genes at two or more loci.

Examples of such traits are stature, skin

color, and eye color. Many polygenic

traits are also influenced by environmental

factors.

genome

The entire genetic makeup of an

individual or species. In humans, it is esti-

mated that each person possesses approxi-

mately 3 billion DNA nucleotides.

variation

In genetics, inherited differences

among individuals; the basis of all evolu-

tionary change.

allele frequency

In a population, the

percentage of all the alleles at a locus

accounted for by one specific allele.

population

Within a species, a community

of individuals where mates are usually

found.

microevolution

Small changes occurring

within species, such as a change in allele

frequencies.

macroevolution

Changes produced only

after many generations, such as the appear-

ance of a new species.

gene flow

Exchange of genes between

populations.

gene pool

The total complement of genes

shared by the reproductive members of a

population.

genetic drift

Evolutionary changes—that

is, changes in allele frequencies—produced

by random factors. Genetic drift is a result

of small population size.

founder effect

A type of genetic drift in

which allele frequencies are altered in small

populations that are taken from, or are

remnants of, larger populations.