Genetics Exam 1

Endocrine System

What is the DNA

The molecule of life

Most humans contain what

46 human chromosomes, 2 meters of DNA, approximately 22,000 genes and 3 Billions DNA base pairs

How many pairs of chromosomes do humans have?

23 pairs of chromosomes (homologous pairs)

What are the DNA bases

A, T, G and C

What is genetics?

It is the study of heredity and variation with a focus on genes

What is gene defined as?

Unit of heredity with the modern definition being that it is a segments of DNA that produces a functional produce such as polypeptide. It also provided the blueprint that determines the trait of an organism

What is a trait?

The characteristic of an organism

what are the four types of large molecules?

Lipids, Nucleic acids, Carbohydrates, proteins

What are the three macromolecules?

Nucleic acid, proteins and Carbohydrates

What are macromolecules made of?

They are polymers constructed from smaller molecules called monomers

How are cellular structures form?

As a result of the interaction of molecules and macromolecules

What is a nucleotide?

Building blocks are used to make long strands of DNA, they are used to make proteins and form chromosomes

Where is the chromosomes contained?

Within the nucleus

How is the characteristic of a cell determined?

The protein it produces

What is the protein that cells make called?

Proteom

Whats an example of a structural protein

Tubulin

What does tubulin do?

Aggregates to form microtubules and plays a role in cell shape and movement

What is does a transport protein do

They are inserted in a cell membrane and help with the transport of ions and small molecules across the membrane

What is an enzyme?

Biological catalyst- they speed up chemical reactions

What are the two types of enzymes?

Catabolic Enzymes and Anabolic Enzymes

Catabolic Enzymes

They breakdown large molecules into smaller ones and provide energy for cells

Anabolic Cells

They are involved in the synthesis of large molecules from smaller ones and provide component for the construction of the cell

DNA?

Deoxyribonucleic acid- genetic material of all living organisms

DNA is a

Polymer of nucleotides, where each nucleotide contains one nitrogenous base

A?

Adenine

T

Thymine

C

Cytosine

G

Guanine

Total amount of chromosomes in humans?

46 Chromosomes

What is a karyotype?

an individual's complete set of chromosomes

Gene expression?

The information within the DNA is accessed during this process

What are the two steps of gene expression?

Transcription and Translation

Transcription?

The genetic information in the DNA is copied into a nucleotide sequence of RNA (ribonucliec acid) (mRnA being the first product)

Translation?

The nucleotide sequence of RNA provides information to make the amino acid sequence of a protein

Central dogma

DNA —→ Transcription —> RNA —→ translation —→ Protein

What are the three traits that organisms display?

Morphological trait, physiological traits and Behavioral traits

Morphological traits

Affects the appearance of the organism (Think physical like the color of a flower or butterfly)

Physiological traits

Affects the function of the organism (Ex: ability to metabolize a sugar)

Behavioral triaits?

Affects the ways an organisms responds to the environment (EX: mating calls of bird species)

Functional product of most genes is?

Polypeptide

Molecular expression of genes

They leads to an organism’s traits

What are the 4 levels of biolgical organization?

• Genes are expressed at a molecular level

• Proteins function at a cellular level

• traits are observed at the organism level

• Genes/traits within a particular species are studied at a population level

Molecular level

Think enzymes and how they function
transcription, gene expression and translation

Cellular level

the structure of the cell that are affected by protein functions
Think proteins and what they do to a cell (blood type)

Organism level

Think physical traits such as the color of a butterfly
traits in an individual

Population level

Think about the population of a species as whole

Define morphs?

Contrasting forms within a single species

Gene variation at a molecular level have 3 types

Gene mutations

changes in chromosome structure
changes in chromosome number

Gene mutations

Differences in gene sequences
leads to two or more expression forms or alleles of the same gene

Changes in chromosome structure

Large segments of a chromosome may be lost, duplicated or reattched to another chromosome

Changes in chromosome number

Single chromosomes may be lost or gained
(a person with Down-syndrome has 47 rather than 46 chromosomes)
A whole extra set of chromosomes may be inherited
(cultivated wheat has 6 sets of chromosomes)

Traits that a person expresses do not result from its genes alone but also from

the interaction between genes and the environment.

Phenylketonuria (PKU)

Involves the interaction between genes and the environment

What does the enzyme phenylalanine hydroxylase do?

Converts phenylalanine to tyrosine

Humans that have one or two functional of this gene can?

metabolize phenylalanine

Humans with two copies of a rare inactive allele cannot?

metabolize phenylalanine, leading to PKU. Phenylalanine will accumulate which will cause detrimental effects

Gregor mendal

Mid 19th century, provided foundation for the science of genetics

Sexually reproducing species are commonly?

Diploid- have two copies of each chromosome (one from each parent)

The two copies of a chromosomes are termed?

Homologs (contain the same genes but not alleles)

Alleles?

Alternative version of a specific gene
Ex: one allele results in dark pigment while another causes light pigment

Sperm and egg are called?

Gametes (haploid)
have one set of 23 chromosomes

What two pair of chromosomes that are not homologues?

Sex chromosomes (X and Y)

Can the genetic makeup of a population change? what is it called?

They can change over time and it is called biological evolution

Natural selection

The process in which individuals with greater reproductive success are more likely to pass their genes to future generations

What are the 6 model organisms?

• E.coli (bacteria)

• Saccharomyces cerevisiae

• Drosophila melanogaster

• Caenorhabditis elegans

• Mus musculus (mice)

• Arabidopsis thaliana

3 fields of genetics

Molecular genetics, transmission genetics, population genetics.

Transmission geneeitcs

Inheritance patterns of a trait that they are passed from parent to offspring (Gregor Mendel)
it uses genetic cross

Molecular genetics

Biochemical understanding of the hereditary material
Gene organization, DNA, RNA and proteins
They study mutant genes that have abnormal functions such as the loss-of-function mutation

Population genetics

Genetic variation of populations

Scientific method

A standard process to validate hypotheses about the natural world

Theory of Pangenesis

Proposed by Hippocrates
“Seeds” are produced by all parts of body
They are collected in the reproductive organs and then transmitted to offspring at moment of conception

Blending theory of inheritance

Factors that control hereditary traits are malleable
They can blend together from generation to generation

Who refuted both theories?

Gregor Mendel

Gregor Mendel

Father of Genetics (1822-1884)

What did he use to study genetics?

Garden pea plants and he also used quantitative analysis. He named it “Experiments on Plant Hybrids” was published in 1866

Hybridization

The mating or crossing between two individuals that have different characteristics

Hybrids

The offspring that results from such mating

Why was the garden pea advantageous

It existed in several varieties with distinct characteristics and its structure allowed for easy crosses where the choice of parental plants could be controlled

What are the two types of crosses?

• self-fertilization

• Cross-fertilization

Self-fertilization

• Pollen and egg are derived from the same plant

• naturally occurs in peas because a modified petal isolated the reproductive structures

Cross-Fertilization

• Pollen and egg derived from different plants

• required removing and planting anthers

What are the seven (morphological characteristics) characters that bred true

Height, flower color, flower position, seed color, seed shape, pod color and pod shape

Eye color is a

Character

Blue eyes is a

Trait

what are the 14 variants

Tall and dwarf

purple and white

Axial and terminal

Yellow and Green

round and wrinkled

Green and yellow

Smooth and constricted

Did Mendel have a hypothesis

No he did not, he used quantitative analysis of crosses may provide mathematical relationships

Mathematical relationships that govern hereditary traits is also called

empirical approach- it is used to deduce empirical laws

What was his first experiment?

It involved crossing two variants of the same characteristics- AKA monohybrid
(flower color)

F1 generation?

The first filial generation resulting from a cross between two parental genotypes. It exhibits traits inherited from both parents.

F2 Generation?

The second filial generation resulting from a cross between two F1 individuals. It shows a recombination of traits inherited from the F1 generation.

What result refuted the blending mechanism of heredity

F1 generation showed only one of the two parental traits
F2 generation showed an approximately 3:! ratio of the two parental traits

Dominant traits

Effects of the variant is seen

Recessive traits

Effects of the variant is not seen

Particulate theory of inheritance

The genetic determinants that govern are inherited as discrete units that remain unchanged as they are passed from parent to offspring

Mendel’s law of segregation

states that during the formation of gametes, the two copies of each hereditary factor segregate so that offspring acquire one factor from each parent.

An individual with identical alleles is termed?

Homozygous.

An individual with two identical alleles is termed

Heterozygous

Genotype is

a specific allelic composition of an individual that determines specific traits.

Phenotype is

The outward appearance of an individual

Punnett square

a grid that enables one to predict the outcome of simple genetic crosses