chap 12,9,10,&11 test Flashcards
1
Q
monomer units which link together to make up the large organic polymers called nucleic acids
A
nucelotides
2
Q
Describe the structure of the monomer unit we call nucleotide
A
- has a phosphate group
- has a pentose sugar
- has a nitrogen-containing base
3
Q
which four nitrogen-containing bases are found in RNA?
A
- adenine (A)
- guanine (G)
- cytosine (C)
- uracil (U)
4
Q
Which four nitrogen-containing bases are found in DNA?
A
- adenine(A)
- guanine (G)
- cytosine (C)
- thymine (T)
5
Q
What are the two nucleic acids which are crucial for life?
A
DNA- contains hereditary information
RNA- uses the information in DNA to make proteins
6
Q
Describe the structure of RNA
A
- is a single strand
- has a backbone of ribose sugars and phosphate groups bonded together
- has adenine, guanine, cytosine, and uracil bonded to each ribose sugar
7
Q
What are the functions of the three types of RNA?
A
- messenger RNA (mRNA): takes genetic information from DNA in the nucleus to ribosomes in the cytoplasm
- ribosomal RNA (rRNA): reads the message delivered by mRNA
- transfer RNA (tRNA): transfers the appropriate amino acids to the ribosome to make a protein
8
Q
Describe the structure of DNA
A
- is double stranded
- has two backbones of deoxyribose sugars and phosphate groups
- the two backbones are joined together by nitrogen-containing bases; adenine, guanine, cytosine, and thymine
- the nitrogen bases are connected by hydrogen bonds
- adenine always binds to thymine; guanine always binds to cytosine; this is known as complementary base pairing
- the paired nitrogen-containing bases are the “rungs” of the ladder formed by the two sugar phosphate backbones
- the DNA “ladder” is helical (spiral)
9
Q
Why is DNA so important? What is its function?
A
it caries hereditary (genetic) information; all the information necessary to create proteins that all organisms need for their life processes
10
Q
What important information did Watson and Crick discover about DNA?
A
they discovered that DNA was composed of two chains held together by nitrogen-containing bases which were held together by hydrogen bonds. The hydrogen-bonded bases make up the “rungs” of the DNA “ladder”
11
Q
What is meant by the term DNA replication?
A
- replication refers to the process of copying a DNA molecule
- a DNA molecule has to be replicated before cellular division occurs so that both of the daughter cells produced contain the exact genetic information as the parent cell did
12
Q
What are the three steps involved in DNA replication?
A
- the DNA ladder unwinds to form two sugar-phosphate backbones, each with only one nitrogen base sticking out at each “rung”
- free nitrogen bases pair with the ones on each of the backbones
- the nitrogen bases form hydrogen bonds, and two daughter double strands are formed from the original double strand of DNA. Each of the daughter double strands are formed from the original molecule of DNA and one new strand
13
Q
a segment of a DNA molecule that contains the information needed to produce a particular sequence of amino acids
A
gene
14
Q
How do genes work?
A
The DNA in a specific gene contains the information necessary to make a specific protein. It passes along this information to RNA which actually makes or synthesizes the protein. This allows genetic information to be expressed as structure and function
15
Q
- refers to the process by which a DNA strand unzips and serves as a template to form RNA
- the information in DNA is “transcribed” or passed along to mRNA
- mRNA tales this information from the nucleus to the cytoplasm
A
transcription
16
Q
- refers to the process by which mRNA leaves the nucleus and goes to ribosomes (rRNA) in the cytoplasm
- rRNA reads the message carried by mRNA and directs tRNA to bring specific amino acid to the ribosome so that a protein can be made
A
translation
17
Q
the “code” tRN uses to bring a specific amino acid to the ribosome
A
codon
18
Q
How do codon’s work?
A
- each one is made up of three of the nitrogen-containing bases and can be thought of as a “word”
- there are 64 different arrangements of the nitrogen-containing bases taken three at a time. This means the genetic language has 64 “words”
- each one is specific to a codon
- since there are only 20 amino acids, there can be more than one codon for each amino acid
- punctuation codons are stop and start signals which act as “capital letters” and “periods” in a sentence. They are found at the beginning and end of each “sentence” or protein
19
Q
refers to the changes in DNA nucleotides
A
mutations
20
Q
What causes mutations?
A
- The change in DNA nucleotides interferes with both transcription and translation and results in different proteins being created
- mutations can be caused by errors during replication or by environmental mutagens
21
Q
How does a point mutation differ from a frameshift mutation?
A
Point mutation
- involves change in only one DNA nucleotide which changes the codon
- results in a protein which can be nonfunctional, have reduced functionality, or not be affected at all
Frameshift mutation
- occurs when a nucleotide is either inserted or deleted from DNA
- results in a protein which is always nonfunctional
22
Q
the development of cancer
A
carcinogenesis
23
Q
What typically causes cancer?
A
A mutated cell
24
Q
What causes mutations?
A
replication errors and environmental mutagens (toxic chemicals, UV radiations, ect.)
25
the spread of cancer to parts of the body other than where it originated
metastasis
26
refers to cell division. During cell division, a parent cell divides to produce two daughter cells. It involves three steps
The cell cycle
27
G1: cell grows and makes identical copies (duplicates) of all its organelles, enzymes, ect.
S: cell replicates its DNA
G2: cell grows and makes final preparations for division
interphase
28
- the cell accurately separates its DNA into two units so that each daughter cell gets an identical copy of the parent cell
- consists of prophase, metaphase, anaphase, and telophase
mitosis
29
the original parent cell divides into two daughter cells
cyokenesis
30
What is the purpose of the cell cycle?
- allows multicellular organisms to grow and develop, and to repair worn out tissues
- allows unicellular organisms to undergo asexual production (plants)
31
How is the cell cycles regulated?
- special signaling proteins called cyclins tell a cell when to divide
- are various checkpoints during the cell cycle at which time apoptosis occurs if there is a problem and the cell cycle can't produce properly
32
Do all cells have the same rate?
no, skin cells and blood cells divide frequently while nervous tissue divides more infrequently if at all
33
What if a cell isn't dividing?
its in the G0 phase
34
Explain how a molecule of DNA is organized into a chromosome
The DNA molecule associates with proteins, which strengthen the DNA, help package it, and control gene activity.
- the nucleosome (DNA + proteins) coils up and produces loops of chromatin
- those loops form condensed chromatin
- The condensed forms a chromosome
- each chromosome contains genes
- each gene gives the information to make only one protein
35
What is this process of "packaging" DNA necessary?
DNA is a fragile molecule. If it didn't become condensed, it would be more likely to break during mitosis
36
What are the three parts of a chromosome?
centromere: holds sister chromatids together until they are separated during mitosis
kinetochore: proteins which bind to chromosomes outside the area of the centromere and attach to spindle fibers to pull the sister chromatids apart during mitosis
telomeres: ends of chromosomes which are more prone to breaking, especially if the individual is old
37
How do homologous chromosomes differ from sister chromatids?
sister chromatids: two identical chromosomes formed after replication, help together at the centromere
homologous chromosomes: two pairs of sister chromatids- one pair coming from the mother and the other pair from the father, are the same length and are held together at the same place by centromeres, and have genes that contain are information for a particular trait at the same area or location
38
How many chromosomes do humans have?
- 46 total chromosomes or 23 pairs
- 23 chromosomes come from the mother in the egg
- 23 chromosomes come from the father in the sperm
39
-chromatin condenses into chromosomes, nuclear envelope begins breaking down, nucleolus disappears
prophase
40
centromeres of sister chromatids line up at the metaphase plate, kinetochores attach to spindle fibers
metaphase
41
two daughter cells are beginning to form, nuclear envelope and nucleolus reappear, and chromosomes become indistinct chromatin
telophase
42
How does cytokinesis differ in animal cells and plant cells?
Animal cells
-a cleavage furrow is formed from a contractile band in the center of the cell and the flexible plasma membrane pinches off to form two distinct daughter cells
Plant cells
-the cell wall is too rigid to pinch off, so a cell plate is formed when vesicles made of cell wall materials migrate to the center of the cell, and once these vesicles fuse, they divide the cell into two daughter cells
43
referred to as reduction division since it results in one-half the number of chromosomes in eggs and sperms
has two cell divisions: I and II
homologous pair of chromosome separate during MI
sister chromatids separate during MII
since DNA replication does not occur between MI and MII, mieosis results in egg and sperm cells
meiosis
44
What is the primary function of meiosis?
Meiosis reduces the number of chromosomes in eggs and sperm by one-half, so that when a sperm fertilizes an egg, you get the same number of chromosomes that the parent had. Without meiosis, organisms would get more and more chromosomes with each generation
45
What is the difference between MI and MII?
Meiosis I: homologous chromosomes are separated
| Meiosis II: sister chromatids are separated
46
Alternate forms of a gene that code for the same trait. For example, the trait "hair color" has different alleles for brown, blonde, red, and black hair
Alleles
47
What happens if an individual has IDENTICAL alleles on homologous chromosomes?
The individual will be homozygous dominant or homozygous recessive for the trait
48
What happens if an individual has DIFFERENT alleles on homologous chromosomes?
the individual will be heterozygous dominant for the trait
49
refers to the exchange of genetic material between non-sister chromatids during prophase of MI
Crossing Over
50
refers to the random alignment of homologous pairs of chromosomes at the middle of the cell during metaphase of MI
independent assortment
51
Whats the difference between diploid and haploid cells?
diploid cells: our body cells. They are made up of 46 chromosomes. Diploid cells are represented as 2N
Haploid cells: our gametes. They are made up of 32 chromosomes. Haploid cells are represented as 1N
52
What is the function of both crossing over and independent assortment?
both result in genetic variability
53
Why are crossing over and independent assortment important?
Genetic diversity results in organisms better suited to survive in their environments
54
What is oogenesis and where does it occur?
egg production in the ovaries
55
How many eggs are formed from one primary oocyte?
one
56
What is spermatogenesis and where does it occur?
sperm production in the testes
57
How many sperm are formed from one primary spermatocyte?
four
58
What happens during fertilization?
the egg and sperm fuse together to form a diploid zygote. After fertilization, the diploid zygote undergoes mitosis in order to grow and develope
59
The 23rd pair of chromosomes in humans. Genetic defects affecting the 23rd pair of chromosomes in an individual affect sexual characteristics plus other characteristics depending on what genes are carried on the chromosomes
sex chromosomes
60
What can happen when chromosomes don't separate correctly during meiosis?
you can get genetic defects
61
What are some examples of these genetic defects?
Down syndrome, Klinefelter's syndrome, XYY syndrome, and Turner syndrome
62
individual with an extra chromosome 21
Down syndrome
63
male individual with an extra X chromosome
Klinefelter's syndrome
64
male individual with an extra Y chromosome
XYY syndrome
65
female individual with only one X chromosome
Turner syndrome
66
a picture of all the chromosomes in one of your body cells.
Karyotype
67
Why do people sometimes have karyotypes done?
They can be done to determine if you have a genetic disorder that involves too many chromosomes or not enough chromosomes
68
What does cell division cycle and meiosis have in common?
DNA duplication during interphase, spindle fibers separate chromosomes, division of chromosomes has a set of stages: prophase, metaphase, anaphase, and telophase
69
What makes cell division cycle different from Meiosis?
produces two identical diploid cells, used for growth and repair in multicellular organisms, used for asexual reproduction in multicellular organisms, has a single cell division, and occurs in body cells
70
What makes meiosis different from cell division cycle?
produces four different haploid cells in sperm and one haploid cell in eggs, promotes genetic variability, used for sexual reproduction in multicellular organisms, has two cell divisions so that the number of chromosomes is divided in half, and occurs in sex cells or gametes
71
Who was Gregor Mendel and why is he important?
Mendel was an Austrian monk who formed the Law of Segregation and the Law of Independent Assortment by cross-pollinating pea plants and examining the characteristics of their offspring
72
Each individual has a pair of alleles for each trait. Alleles are separated when eggs and sperm are formed, so each egg or sperm gets only one allele.
Law of Segregation
