Block 1: Nucleic acids and genetic information: week 2

Question 1

what is Chromatin?

Answer 1

Chromatin is loosly packed DNA strands found in the nucleus.

Question 2

what is a Nucleosome?

Answer 2

Nucleosomes are units of dna that make up chromatin.A Nuclosome structure is DNA wrapped around a histone protein twice witth a linker DNA connecting the them together.

Question 3

What happens to chromatin when the cell is about to undergo division?

Answer 3

The chromatin condenses more tightly by continous coiling and wraping around itself to then form chromosome.

Question 4

What is the human karyotype?

Answer 4

The karyotype is the sterotypic number, shape and size of chomosomes during metaphase.

Question 5

how many chomosomes are there?

Answer 5

there are 46 chromosomes in total

23 paternal and 23 maternal

Question 6

How many sex chromosomes are there?

Answer 6

you inherit 1 sex chromosome from each parent ( maternal and perternal) so of the 23 chromosomes 1 is a sex chromosome.

Question 7

what the name of a chromosome that is not a sex chromosome?

Answer 7

This is called an autosome.

Question 8

what is a telomere?

Answer 8

A telomere is the ends of the chromosome that protect it.

Question 9

where is the p arm?

Answer 9

the upper part of the chomosome

Question 10

where is the q arm?

Answer 10

The q arm is the btoom half of the chromosome.

Question 11

What is the centromere?

Answer 11

center of the chromosome and is also where spindle attachment occurs.

Question 12

what is the promoter region?

Answer 12

The promoter region is where transcription factors attch to control transcrption.

Question 13

what are transcrption factors?

Answer 13

Transcription factors influnce gene expression by regulating RNA activity.

Question 14

what causes cyctic fibrosis?

Answer 14

Cystic fibrosis is a disease that is caused by an abnormal gene. An abnormal gene is called a genetic mutation. The gene that causes problems in CF is found on the seventh chromosome.

Question 15

what causes down syndrome?

Answer 15

children are born with an extra chromosome of chromosome 21.

Question 16

What is klinefelter syndrome?

Answer 16

Klinefelter syndrome is where boys and men are born with an extra X chromosome.

Question 17

what are the steps in a cell cycle?

Answer 17

The cell cylce has the mitotic phase and interphase.

Question 18

What are the phases in interphase?

Answer 18

G1
G0
S1
and 
G2

Question 19

What happens at each of the phases of interphase?

Answer 19

G0- cell isnt dividing, its resting until it receives a signal to enter the cycle.
G1- cell grows, increased amount of oganells, increased protein synthesis
S1- DNA in cell duplicates to prepare for division
G2- cell onstious to grow futher and undergoes checks to ensure its ready for mitosis.

Question 20

what can have an effect on mitosis?

Answer 20

medical procedures such as chemotherapy
or
medications ( drugs)

Question 21

what happens during mitosis? (inluding each step)

Answer 21

Prophase-chromosome condensation, disperal of the nuceli .centriols split and move to each poll and spindles start to form
Prometaphase- nuclear evelope fragmentation, attachment opf spindles to centromeres on chromosome.chromosomes start to move to the center.
Metaphase- chromosomes alligment at the metaphase plate
Anaphase- chromosomes move to opposite cell plates(polls)
Telophase- chromosomes uncoil, nucleoli develop and fuse, disassembly of spindle and reformation of nuclear envelope.
cytokinesis- cytoplasm divides and two daughter cells are formed as a result.

Question 22

what is a nucleotide?

Answer 22

nucleotide is a molecule consisting of a nitrogenous base, phosphate group and sugar residual.

Question 23

How man bases are there for nucleotides?

Answer 23

There are 4 bases
guanine
adenine
cytosine
thymine (uricil in RNA)

Question 24

How many hydrogen bonds are found between each of the bases?

Answer 24

adenine and thymine have 2 hydrogen bonds between them.

cytosine and guanine have 3 hydrogen bonds between them.

Question 25

what is the name of the bonds that form the DNA back bone?

Answer 25

The phosphodiester bonds

Question 26

what proteins wound around DNA?

Answer 26

Histone proteins

Question 27

what is a chromatid?

Answer 27

A copy of one duplicated chromosome

Question 28

What is a gene?

Answer 28

A unit of biological information, a distinct sequence of nucleotides forming part of a chromosome.

Question 29

How does the genetic code enable a protein sequence to be deduced from a gene sequence?

Answer 29

The trandormation of genetic infomation to protein synthesis depends on the genetic code. mature MRNA formed during transcrption and splicing, carries triplet condons which are the same to the genetic code and complementery to TRNA which being amino acids. The genetic code is also degenerate as a single amino acid may have other ways that could allow it to be synthesised.

Question 30

Distinguish between the Antisense DNA and the Sense DNA?

Answer 30

DNA has a double helix structure . the sense strand goes from 5-3 whilst the antisense strand foes from 2-5. when RNA polymerase reads the stand it reads from the antisense strand to make a mrna sequnce which is the same as the sense strand.

Question 31

How does preMRNA become matureMRNA?

Answer 31

During transcrption RNA plymnerase reads the anti-sense stand to form a MRNA sequnce which is the same as the sense strand. But this cannot leave the nucleus until it becomes mature MRNA.
the preMRNA first undergoes splicing which removes intorns from the sequence and leaves exons. Then undergoes capping which adds a polyadeylation bases on one end and MGTP on one end.

Question 32

What is used during capping of MRNA?

Answer 32

MGTP
and
Polyadenylation

Question 33

what can futher regulate the matureMRNA when it enters the cytoplasm? (RNA splicing)

Answer 33

MIcroRNA can futher regulate mature MRNA.

Question 34

How do ribosomes start and end the sequence bneing translated?

Answer 34

methonine- start

stop codon- releasing factor.