Biology 288-Lecture 6

Cell Biology

What is the relationship between DNA and heredity?

Heredity information is coded for by DNA

Before it was discovered that DNA coded for genetic information, what was the initial assumption?

It was assumed that proteins coded for genetic information

Adenine, Guanine, Cytosine, and Thymine are the nucleotides which make up the DNA backbone, how do these differ from the nucleotides found in RNA and proteins?

They thymine in RNA is replaced by a Uracil group instead

What type of bonds hold together the DNA backbone?

Phosphodiester bonds

What kind of bonds hold the DNA bases together?

Hydrogen bonds

Which carbon is the nucleotide base bonded to?

The 1’ carbon

What molecule allows Uracil to replace Thymine during transcription from DNA-RNA?

BrDU

If a radiated base pair was added to a DNA sample prior to replication, and the radiation was detected in the newly synthesized DNA what does this indicate?

This indicates that the base pairs were incorporated into the DNA during replication

What is the main function of chromosomes?

Chromosomes organize and carry genetic information

What is the purpose of color coding chromosomes?

Allows us to differentiate between specific genes

What determines if a gene needs to be transcribed?

A cell

Which enzyme is responsible for starting the process of transcription?

The promoter

What is necessary in order for the promoter to recognize a certain area of a gene for transcription?

The promoter region

What is the promoter region?

Allows the transcription factor to bind DNA molecules and initiate transcription

is the duplication of more chromosomes than needed always lead to something bad?

Not always, it depends

What is the purpose of sexual reproduction

Genetic variation

Why does the cell store protein in excess prior to the initiation of cell division?

Because the proteins cannot be produced later during cell division

During replication, what is the first thing to be replicated?

The mitochondria

Why is the mitochondria replicated first during cell division?

Division requires a lot of energy from the cell

Before chromosme can divide they undergo _________.

Condensation

What is the function of the centromeres?

They bind to the center of the chromosme and allow the chromosomes to bind to the mitotic spindle

Why are proteins not divided equally between daughter cells when the cell divides?

They are divided based on need, some cells need more proteins than others

What is the main function of a stem cell?

Generate specialized cells

When a stem cell divides into 2, how many specialized cells will be produced?

Only 1

Why does stem cell division only produce one specialized cell?

The stem cell must keep one of the daughter cells undifferentiated in order to allow for the stem cell genes to be passed down

What is the function of telomeres?

Prevent chromosme ends from fusion and from being recognized as a site of DNA damage

What are telomeres composed of?

Purine repeats

How does a telomere prevent a chromosome from being cut?

It takes the damage instead

How can the length of a telomere be used to determine the age of a chromosome?

The more the cell replicates, the more it repairs so the more the telomeres take damage. Chromosome from older cells will typically be shorter as they have taken more damage

What is the downside of having telomeres which are shorter?

It impedes the cell’s ability to repair

If cells had more telomeres, they would be able to avoid damage longer and thus live longer, can we just incorporate telomeres into a cell in order to extend its life?

No, this hasn’t worked yet