BSI Lecture 4 DNA Structure Flashcards Preview

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Flashcards in BSI Lecture 4 DNA Structure Deck (54):
1

Chromosomes

contain long strands of DNA and associated proteins

2

How many chromosomes do humans have?

46

3

How many pairs of autosomes (non-sex chromosomes) do humans have?

22

4

What are the types of sex chromosomes?

X and Y

5

What is a Karyotype?

It is the display of all chromosomes in a cell

6

What is an allele?

One of two or more alternative forms of a gene that arise by a mutation and are found in the same place on a chromosome

7

What constitutes a normal Karyotype?

Humans have 46 chromosomes total. 22 pairs of autosomes (non-sex chromosomes) and a pair of XX or X and Y sex chromosome

8

When does the chromosomes have to be packaged very tightly in an organized manner?

During mitosis

9

When preparing for division, DNA is packed into the _________ chromosomes.

Mitotic

10

How many levels of packaging are there?

4

11

What level of packaging is it when threadlike mass of genetic material (DNA and histone proteins) form "beads on a string" (11nm structure)?

Level 1

12

What is a nucleosome?

Basic structural unit of a chromosome. Histones, DNA, Linker Region

13

How many turns of DNA helix are wound around the octomeric core of histones?

2

14

What is the role of histones in DNA packaging?

Acts as spools for DNA helix to wrap around its octomeric core.

15

What is a linker region?

A linker region is the DNA you see between the two histones or "beads"

16

Octomeric core consists of two copies of each of the 4 core histone protein ____, ____, ____, and ____

H2A, H2B, H3, H4

17

Histones are contained in the _______ ________

octomeric core

18

Level 2 packaging, what is the chromatin fiber width?

30nm

19

What is the purpose of DNA packaging?

Organize and fit all of the DNA into the nucleus.

20

What is the difference between mitotic chromosome and an interphase chromosome?

Mitotic chromosomes are ready for replication and interphase chromosomes are not.

21

Can the same gene produce mRNA and tRNA?

No

22

Do genes encode lipids and carbohydrates?

No, only proteins are encoded. Lipids and carbohydrates are synthesized.

23

Loops are condensed into chromosomes (700nm). At what level does this occur?

Level 4

24

What are telomeres?

DNA sequence at the ends of the chromosomes

25

Telomeres are repeated DNA sequences which allow the ends of chromosomes to be replicated and also to protect the ends from being mistaken by the cell as broken DNA

True

26

What is a chromatid?

One of the paired and parallel strands of a duplicated chromosome joined by a single centromere.

27

What is a sister chromatid?

A duplicate copy of a chromatid joined by the centromere.

28

What is a centromere?

Specialized DNA sequence that allows duplicated chromosomes to be separated during mitosis.

29

Where do the mitotic spindle binds?

Centromere

30

________ is the part of the cell cycle when the cell is not dividing.

Interphase

31

Packaging of interphase: What percent of the chromosome are highly condensed?

10%

32

What are heterochromatin?

Highly condensed chromosome

33

Genes that are considered "off" are located in areas of ______________

heterochromatin

34

Most regions of the interphase chromosome are less condensed, these area is called ____________

Euchromatin

35

What level of mitotic chromosome does euchromatin resemble?

Level 2

36

Each strand of DNA is made up of ________

Nucleotides (deoxyribose, phosphate, and base)

37

DNA strands run in _________ direction.

Opposite

38

DNA strands are held together by hydrogen bonds between ________

Bases

39

The backbone of the DNA strand is called the _________

Sugar-phosphate backbone

40

The two strands of nucleotides forms a ________

Double helix

41

The basic building blocks of a nucleotide are

Ribose (sugar), phosphate, and a base

42

Nucleoside consists of

ribose and base (no phosphate)

43

What are the 2 Purines and are they single or doubled ringed?

Adenine and Guanine, they are double ringed

44

What are the 3 Pyrimidines and are they single or doubled ringed?

Cytosine, Thymine, and Uracil, they are single ringed.

45

How are nucleotides linked?

Via phosphodiester bonds to form a strand of DNA

46

What bond forms between 3'-OH group of one sugar and 5'-phosphate group of another?

Phosphodiester bonds

47

Define: Gene

A gene is usually defined as a segment of DNA that contains the instructions for making a particular protein (or RNA, if that is the final product).

48

What type of RNA is the only one translated into protein?

mRNA

49

What are the "other" types of RNA?

snRNA, miRNA

50

RNA are single or double stranded molecules?

single

51

RNA is composed of ______________ acids

ribonucleic

52

RNA has an OH group at the _____' position of sugar.

2'

53

Besides complementary pairing, what are the other functions of Purines and Pyrimidine?

Energy, metabolism, protein synthesis, regulation of enzyme activity and signal transduction

54

The difference between ribose and deoxyribose is that ribose has an "OH" and deoxyribose has a single "H" at which carbon?

2'

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