Biology - Control of Gene Expression

the overall process of genetic information flowing from genes to proteins; genotype to phenotype:

gene expression

Scientists say that the gene has been expressed when:

it is transcribed and its product has been synthesized

in prokaryotes genes are turned on and off by what?

environmental factors

if all genes were turned on at the same time what would occur?

metabolic disorder

True or False: bacterium have multiple DNA molecules

False

a group of genes with related functions in a prokaryote:

operon

an operon is made up of what?

structural genes and a promoter region

genes that code for the protein product on the operon:

structural genes

genes that promote the movement of RNA polymerase onto the structural genes:

promoter genes

the promoter area is made up of which two things?

promoter gene and operator gene

a region of the DNA that acts as an on-off switch for an operon:

operator

this part of the operon is located somewhere else on the DNA:

regulator

what does the regulator gene produce?

repressor proteins

in *trp* operon, how is the operon turned off?

when a large amount of tryptophan accumulates, one molecule binds to the repressor. then the repressor binds to the operator, turning it off.

when is the *lac* operon turned “off”?

when there is no lactose in the cell’s enviornment

Cancer results from:

mutations in genes that control cell division

How can viruses cause cancer?

They carry cancer-causing genes that are inserted into a host cell, making it cancerous

an altered version of a gene found in normal cells:

oncogene

mutations can change a ______ into a oncogene:

proto-oncogene

what are proto-oncogenes?

normal genes that promote cell division and have the potential to become an oncogene

what are the three kinds of changes in somatic cell DNA that can produce oncogene?

mutation in the gene, an error in DNA replication, movement of gene

result of mutations within genes:

hyperactive growth-stimulating protein in normal amount

result of an error in DNA replication:

normal growth-stimulating protein in excess

result of gene moving from its normal location:

normal growth-stimulating protein in excess

these proteins stimulate cell division:

growth factors

genes whose products inhibit cell division are called:

tumor supressor genes

when there is a mutation in the tumor-suppressor gene, what happens?

cell division is uncontrolled, resulting in cancer

colon cancer steps:

increased cell divison, growth of benign tumor, growth of malignant tumor

what is needed to produce a full-fledged cancer cell?

four or more somatic mutations

which gene puts women at a high risk of breast cancer?

a gene on chromosome 17 called BRCA1

what are some carcinogens?

asbestos, X-rays, UV rays, cigarette smoking, vaping, chewing tobacco

A:

promoter

B:

regulatory gene

C:

mRNA

D:

protein

E:

inactive repressor

F:

RNA polymerase

G:

promoter region

H:

operator

I:

genes

J:

*trp* operon

K

tryptophan molecule

L:

active repressor

eukaryote cells are _______ according to the functions they perform:

differentiated

eukaryotic genes are turned on or off depending on:

the stage of development or environment factors

what did F. C. Steward find?

differentiated carrot cells could grow into adult cells that were identical to the parent plant

cells with the potential to grow into any cell:

totipotent

DNA is a single chromosome is how long?

4 centimeters long

DNA and histones proteins make up:

nucleosomes

each nucleosome consists of what?

a DNA segment and eight histone molecules

DNA packing prevents gene expression by:

prevening transcription proteins from accessing DNA

to initiate transcription, this must happen:

RNA polymerase must bind to the promoter region adjacent to a gene

what assists RNA polymerase in attaching to the promoter region?

transcription factors

RNA polymerase and transcription factors form a:

transcription initiation complex

these assist the transcription initation complex:

enhancers

these transcription factors bind to enhancer regions away from the gene:

activators

in order to bring the activators close to the gene, what has to occur?

the DNA bends due to a DNA-bending protein

RNA processing includes:

RNA splicing, addition of cap and tail

in the fruit fly, the differences between male and female are due to:

alternative RNA splicing

human RNA can be spliced in how many different ways?

7

how do the location of the cap and tail change the expression of the RNA?

changes the length

how is passage of mRNA through the nuclear envelope controlled?

molecules attached to pre mRNA prevent its passage into the cytoplasm until RNA processing is complete.

these molecules prevent translation if other molecules are not available:

inhibitory proteins

these molecules bind to sequences at the 5’ end of the mRNA, preventing the attachment of ribosomes:

regulatory proteins

enzymes in the cytoplasm attack this part of the mRNA molecule first:

poly-A tail

name three ways that proteins are modified to become functional:

cut into two or more chains, more molecules are attached, protein is transported to specific locations

how is insulin activated?

it is cut

what does breaking down proteins allow the cell to do?

this allows the cell to adjust the kinds and amount of proteins in response to changes in the enviornment

nuclear transplantation:

replacing the nucleus of an egg cell or a zygote with the nucleus of an adult somatic cell

early embryo is also called:

blastocyst

two kinds of cloning:

reproductive cloning and therapeutic cloning

describe reproductive cloning:

cloning of nonhuman mammals to create a genetically identical animal

how is cloning used in agriculture?

scientists are cloning farm animals with a desired set of characteristics. by cloning pigs with a certain set of genes, this allows them to provide organs for human transplant.

therapeutic cloning

cloning in which an embryo is produced, which produces embryonic stem cells. these stem cells can become any kind of differentiated cell

after fertilization of a fruit fly egg, what occurs?

different concentrations of proteins produced by the dividing cells determine polarity, which is the top, bottom, anterior, and posterior regions

what do the different concentrations of proteins during fruit fly fertilization activate?

they activate specific embryonic genes for segmentation

general regions of head, thorax, and abdomen are established by:

gap genes

specific formation of each body segment is established by:

pair rule genes

formation of body parts is established by:

homeotic genes

where are homeotic genes found:

in clusters on chromsomes

homeotic genes encode these proteins:

transcription factors

common sequence of 180 base pairs that codes for 60 amino acids found in the homeotic genes:

homeobox

what do the hox genes produce?

they code for a part in the homeotic transcription factors. this region can bind to a promoter, which turns a gene on and off

fruit flies scientific name

drosophila

growth of legs on the head instead of antennae:

antennapedia mutation

what are the stages of fruit fly development?

egg, larva, pupa, adult

define “gap” gene

Gap genes are a class of genes involved in the early development of an embryo. They are responsible for dividing the embryo into broad regions along the anterior-posterior axis. Gap genes are expressed in broad domains that overlap with one another, and their expression patterns help to establish the initial spatial coordinates of the embryo. Mutations in gap genes can lead to severe developmental defects.

define pair rule gene

Pair rule genes are a class of genes that are involved in the segmentation of the developing embryo in animals. They are responsible for dividing the embryo into a series of segments, each of which will give rise to a specific body part. Pair rule genes are activated in a striped pattern along the anterior-posterior axis of the embryo, and their expression is regulated by the maternal and gap genes. Mutations in pair rule genes can lead to defects in segmentation and patterning of the embryo.

Why is it likely that ancestors of fruit flies had 2 pair of wings? What gene causes them to have only one pair of wings?

It is likely that the ancestors of fruit flies had 2 pairs of wings because other insects, such as dragonflies and mayflies, also have 2 pairs. Evolution could have activated the gene responsible for one pair of wings, which is called Ultrabithorax (Ubx).

What are hox genes? What might occur if a hox gene mutated?

Hox genes are a group of genes that control the body plan of an embryo along the head-tail axis. They play a crucial role in determining the identity and positioning of body segments during development. If a hox gene mutates, it can cause developmental abnormalities, such as the formation of extra or missing body parts, or the transformation of one body part into another.

kruppul mutant flies description:

these flies are missing their thoracic segments

fushi tarazu mutant flies description:

missing every other segment

Ubx mutant flies description

extra pair of wings

Antp mutant flies description:

legs form where the antennae should be

What will happen to an embryo that doesn't have BICOID protein?

the embryo will develop without any anterior structures and will die

What will happen if BICOID is overexpressed?

the embryo will develop more anterior structures and less posterior structures, and eventually die

what kind of gene is HAIRY?

pair-rule gene

what kind of gene is EYELESS

homeotic gene

A:

distal control element

B:

activators