EXAM 4-BIO

words to know for exam 4

DNA is semi-conservative

hat each of the two strands in double-stranded DNA acts as a template to produce two new strands

Replication relies on complementary base pairing,

that is the principle explained by Chargaff's rules: adenine (A) always bonds with thymine (T) and cytosine (C) always bonds with guanine (G).

sketch a replication bubble label on it the 5’ and 3’ ends, the origin of replication,
replication forks, as well as the direction of the leading and lagging strands

helicase function

An enzyme that breaks hydrogen bonds between nucleotides of DNA, "unzipping" a double-stranded DNA molecule.

DNA replication is described as bidirectional

because DNA replication proceeds outward from two replication forks.

During what process are parental DNA strands used as templates for the synthesis of new DNA strands?

replication

Why do eukaryotic cells have multiple origins of replication?

To ensure timely replication of multiple, relatively large chromosomes

DNA Ligase

an enzyme that joins pieces of DNA by catalyzing the formation of a phosphodiester bond between the pieces.

DNA polymerase

Any enzyme that catalyzes synthesis of DNA from deoxyribonucleotides.

double helix

The secondary structure of DNA, consisting of two antiparallel DNA strands wound around each other.

lagging strand

In DNA replication, the new strand of DNA that is synthesized discontinuously.

leading strand

In DNA replication, the new strand of DNA that is synthesized in one continuous piece .

Okazaki fragments

Short segments of DNA produced during replication of the lagging strand.

origin of replication

The site on a chromosome at which DNA replication begins.

primer

A short, single-stranded RNA molecule that base-pairs with a DNA template strand and is used as a starting point for DNA synthesis by DNA polymerase.

replication fork

The Y-shaped site at which a double-stranded molecule of DNA is separated into two single strands for replication.

Daughter DNA

he new DNA strand that grows continuously in the 5' to 3' direction.

Primase is in charge of

synthesizing a RNA primer and provide a 3' end

Topoisomerase is in charge of

relieving torque stress

Ligase is charge of

closing the gap between Okazaki fragments

DNA polymerase III is in charge of

synthesizing the daughter strand

DNA is a semiconservative process meaning

each parental strand serves as a template strand for a daughter

DNA helicase is in charge of

untwisting the double helix

7 different proteins and enzymes

DNA helicase, single-stranded binding proteins, Topoisomerase, primase, DNA polymerase III, ligase

DNA polymerase I

replacing an RNA primer with DNA nucleotides

single strand binding proteins

Keep DNA strands from repairing

leading strand

made continuously, made in segments, the daughter strand elongates away the replication fork, only one primer needed, synthesized 5-3

lagging strand

daughter strand elongates towards from the replication fork, synthesized 5-3, multiple primers needed

order of events of synthesizing Okazaki fragments

1. DNA polymerase 3 binds to three end of primer B
2. DNA polymerase 3 moves 5-3 elongating the fragment B
3.DNA polymerase 1 replaces primer A with DNA
4.DNA ligase OKASAKI FRAGMENTS a &b

life cycle

shows the role of mitosis and meiosis in the life of an individual

zygote

2n, diploid, 1 cell

How is a zygote created

fertilization

fertilization

fusion of sperm and egg

Meiosis

-type of nuclear division
-produces gametes/haploid cells
- reduces the# of genetic material in half

gametes

sperm and egg

M phase

The phase of cell division in which replicated chromosomes are pulled apart.

Interphase

The phase of the cell cycle in which a cell spends most of its life.

S phase

The phase of the cell cycle in which DNA is replicated.

G2 phase

Phase of the cell cycle where the cell synthesizes the proteins necessary for chromosome sorting and cell division.

G1 phase

A period when a cell may become committed to divide based on the environmental conditions and the presence of signaling molecules.

sex chromosomes

Chromosomes that determine the sex of an individual.

Interphase starts with

G1

order of phases

-prophase
-prometaphase
-metaphase
-anaphase
-telophase
-cytokenisis

allele

A particular version of a gene.

autosome

Any chromosome other than a sex chromosome.

dominant

Referring to an allele that determines the same phenotype when it is present in heterozygous form.

gene

The hereditary determinant of a trait or a section of DNA that codes for a protein.

The hereditary determinant of a trait or a section of DNA that codes for a protein.

genotype

All the alleles of a gene or genes present in a given individual.

heterozygous

Having two different alleles of a gene

homozygous

Having two identical alleles of a gene.

phenotype

The detectable traits of an individual.

recessive

Referring to an allele whose phenotypic effect is observed only in homozygous individuals

sex chromosomes

Chromosomes that differ in shape or in number in males and female.

true breeding line

a variety of a species that exhibits the same trait after several generations of self-fertilization

P (parental) generation

true breeding parents in Mendel's experiments

F1 generation

offspring of the P generation

F2 generation

offspring of the F1 generation

Aneuploidy

An alteration in the number of a particular chromosome, so the total number of chromosomes is not an exact multiple of a set.

crossing over

The exchange of corresponding segments of non-sister chromatids between a pair of homologous chromosomes during meiosis I.

diploid

Having two sets of chromosomes, one inherited from the mother and the other set inherited from the father.

fertilization

Fusion of the nuclei of two gametes (haploid cells) to form a zygote (diploid cell).

gametes

A haploid reproductive cell.

haploid

Having one set of chromosomes.

homologous chromosome pair

In diploid organisms, a pair of chromosomes that are the same size and shape and contain the same genes in the same positions.

nondisjunction

An error that can occur during meiosis or mitosis; it results in one daughter cell receiving two copies of a particular chromosomes while the other daughter cell receives none.

sister chromatids

The paired, double-stranded DNA copies of a recently replicated chromosomes.

Sexual reproduction

A process in which two haploid gametes unite to form a genetically unique diploid cell.

Monosomy

The condition of having a diploid chromosome complement in which one chromosome lacks its homologous partner.

Trisomy

The condition in which there are three copies of the a chromosomes type instead of the normal two.

Life cycle

The sequence of events that produces another generation of organisms

generates genetic diversity in 3 ways

random fertilization, independent assortment, and crossing over

when does crossing over happen

prophase 1

what happens in random fertilization

gametes fuse independently of their genetic information

principles of chromosome theory of inheritance

1. DNA is genetic material
2. Chromosomes are inherited as units from parents to offspring
3.Diploid cells contain pairs of homologous chromosomes( 1 maternal and 1 paternal)
4.During Meiosis I-homologs separate and sort independently of whether they are maternal or paternal
5. Gametes are haploid--> carry one set of chromosome

How is DNA organized?

chromosomes

how else are chromosomes inherited?

cell to cell through mitosis and from pare4nts to offspring

What do homologous chromosomes carry?

a set of complimentary genes

Gene expression

|Gene-->|protein-->| characteristic|

What is a gene?

Unit factor passed on from generation to generation)(ex. eye color seed color)

What is an allele?

variant form of a gene

character

a distinguished feature of a group or organism that is heritable and controlled by genes

what is a trait

variation of a character controlled by alleles

Genotype

description of
the genetic makeup of
an individua

Phenotype

observable, measurable
characteristics in an
individual
(described by adjectives)

diploid organisms carry

y two alleles per gene
(one in a each chromosome within a pair of homologs)

RR or rr

> homozygous (two identical alleles)

RR

--> homozygous dominant

rr

--> homozygous recessive

Rr

--> heterozygous (two unequal alleles)

capitalized letter

dominant

lower case letter

recessive

punnet square

tool for predicting outcome of a
genetic cross

square

male

circle

female

filled in circle or square

affected

empty circle or squar

unaffected

recessive trait

*unaffected individuals may have effected children
*may skip generations
*heterozygous individuals are carriers
* males and females effected with equal frequency

sex linked genes

found only on sex chromosomes

y chromosome

75 genes mostly in masculenity