12: Reproductive system Flashcards
1
Q
Where are nucleic acids found?
A
Nuclei of cells
2
Q
What organic macromolecules are nucleic acids made up of?
A
Carbon, hydrogen, oxygen, nitrogen, phosphorus
3
Q
What is a monomer?
A
Molecule that can be bonded to other identical molecules to form a polymer
4
Q
What are polynucleotides?
A
A chain of repeating monomers called nucleotides
5
Q
What 3 things make up a nucleotide?
A
- pentose sugar - deoxyribose, ribose
- phosphate group
- nitrogenous base - adenine, guanine, cytosine, thymine, uracil.
6
Q
What is a nucleoside made of?
A
Pentose sugar (deoxyribose + ribose) and nitrogenous base
7
Q
Nucleotide is made of nucleoside and what other item?
A
Nucleoside + phosphate group
8
Q
In what way does nitrogenous bases carries the information?
A
By their sequence
9
Q
What are the 2 major classes of nucleic acids
A
Deoxyribonucleic acid (DNA), ribonucleic acid (RNA)
10
Q
Where are DNA found in the cell?
A
Mainly in nucleus, also in mitochondria
11
Q
Approx how many genes are in human genome?
A
20,000 - 25,000
12
Q
What does DNA do?
A
Constitutes the blueprint that codes for protein synthesis
13
Q
____% of DNA is due to genes
A
1.5
14
Q
____% of DNA is non-coding, e.g. regulatory sequences, introns, and non-coding DNA, e.g. repeat elements
A
98.5%
15
Q
What does DNA stand for?
A
Deoxyribonucleic acid
16
Q
What does the non-coding DNA do?
A
Regulate the coding of the coding DNA
17
Q
What are the coding DNA called?
A
Genes
18
Q
How does genome size compares to gene number, in humans vs other organisms
A
It is random, not positively correlated. Human can have smaller genome size than chimps, but greater gene number than chimps.
19
Q
What is the base pairing rule of the nitrogenous bases in DNA? (which matches with what)
A
A - T, C - G
20
Q
DNA wrapped around proteins called _________
A
Histones
21
Q
Histones and DNA bundled together called a _____________
A
Chromatin
22
Q
Chromatin twists and condense to form _______________
A
Chromosomes
23
Q
Each _____________ contains hundreds to thousands of genes
A
Chromosome
24
Q
What does somatic mean?
A
Affecting/characteristics of the body as opposed to the mind or spirit.
25
Each somatic human cell nucleus has _____(number) copies of each chromosome. Inherited from who?
2, one from mum, one from dad
26
How many chromosomes, how many pairs of them = full amount of DNA?
46 chromosomes, 23 pairs
27
What does diploid mean?
A pair of chromosome, one from mum, one from dad
28
A diploid cell is also called a ____________ chromosome, because one chromosome is from mum, one from dad.
Homologous
29
Gametes have ___(number) chromosome, of each homologous pair. Because if it is a half set, we call it a _________ chromosome
1, haploid
30
What does autosomal chromosome means?
They don't have any bearing on the gender of a person
31
Humans have ___ pairs of autosomal chromosomes and ____ pair of sex chromosomes
22, 1
32
What is a karyotype?
A map of chromosomes in a dividing cell.
33
What is a map of chromosomes in a dividing cell called?
Karyotype
34
What does RNA stands for?
Ribonucleic acid
35
Describe the structure of an RNA.
Single stranded polymer, self complementary sequences forms folds, bulges and helices
36
Where are RNA found in the cell?
Nucleus and cytoplasm.
37
Difference of the pentose sugar in RNA vs DNA
RNA's ribose, DNA's deoxyribose
38
What of the nitrogenous bases of DNA is replaced in RNA?
Thymine by Uracil
39
What are the 3 types of RNAs? What are their main roles?
mRNA - messenger RNA, carries info from DNA to ribosomes through transcription
tRNA - transfer RNA, bring amino acid to ribosomes for production of proteins via translation
rRNA - ribosomal RNA, integral part of ribosome
40
Define genetics
Study of heredity
41
What is a gene?
A segment of DNA that codes for a protein.
42
Define allele.
Alternative form of a gene. E.g. in a pair of chromosome, a small part of one side of it contains gene of one eye color, the parallel part of the other chromosome contains gene that can be for another eye color.
43
What is the difference between genotype and phenotype?
Genotype is the actual gene (AA, Aa, aa) and phenotype is the person's appearance (blue eyes and brown eyes)
44
What are sex-linked traits?
Traits affected by genes on sex chromosomes.
45
There is at least ________(number) of proteins in our body.
10,000
46
Proteins accounts for about ___% of the dry body weight, and collagen is about ____(proportion) of total protein in the body
42, 1/4
47
Proteins contain _____, ______, ______, _______ bound by covalent bonds
Carbon, hydrogen, oxygen, nitrogen
48
Apart from carbon, hydrogen, oxygen and nitrogen, proteins may contain other elements such as _______, ________, ______, ______
Sulphur, phosphorus, iron, iodine
49
Proteins are made up of long chain of __________, linked to each other by peptide bonds.
Amino acids
50
What is the part of the amino acid not involved in linking to each other called? What function does it have?
Side chains. Each amino acid has specific properties due to these side chains.
51
Humans have how many types of amino acids?
20
52
What are the 3 types of amino acids, and how many of them are for each type?
Essential aa (9), non-essential aa (5), conditional aa (6)
53
What is the structure of an amino acid?
1 Amine group + 1 carboxyl group + 1 hydrogen atom + 1 side chain
54
What are the possible characteristics of the side chains of amino acids?
Some are non-polar and hydrophobic; some hydrophilic; or positively/negatively charged
55
How do you call 2 amino acids linked together?
Dipeptide
56
How do you call 3-10 amino acids linked together?
Oligopeptide
57
How do you call 10 or more amino acids linked together?
Polypeptide
58
How do you call 50 amino acids linked together?
Protein
59
What kind of amino acids cannot be made by our bodies that need to be acquired through diet?
Essential AA
60
What kind of amino acid can be synthesized in the human body?
Non-essential AA
61
What type of amino acid is a conditional amino acid?
Non-essential AA
62
When does conditional amino acid becomes essential?
When you are ill or stressed.
63
What are the 6 roles of proteins?
Regulation, transport, protection, contraction, structure, energy.
64
How does proteins regulate our body?
Enzymes control chemical reactions; Hormones regulate many physiological processes.
65
How does proteins 'transport'?
- Hemaglobin transports oxygen and CO2 in the blood
- Plasma proteins transport many substances in the blood
- Proteins in plasma membranes control movement of materials in and out of the cells
66
How does proteins function as a protection in our body?
As antibodies that protect against microorganisms and other foreign substances
67
What are the proteins that are responsible for muscle contraction?
Actin and myosin
68
How does proteins maintain structure in our body?
- Collagen fibers form structural framework in many parts of the body.
- Keratin adds strength to skin, hair and nails.
69
How does proteins generate energy?
Broken down for energy, yield as much energy as carbs do.
70
What is the recommended % intake of proteins in calories?
10-35%
71
What affects the way protein folds and take shape?
Interaction between side groups in a long chain + peptide bonds
72
What are the 4 levels of protein structure?
Primary, secondary, tertiary, quaternary
73
What is a primary protein structure?
Sequence of amino acids linked by peptide bonds
74
What is the secondary protein structure?
Proteins folds to form secondary structures because the aa have different side chains.
2 regular folding patterns:
- Alpha helices (keratin)
- beta pleated sheets (fibroin, silk)
75
What is a tertiary protein structure?
3D shape determined by folding of a secondary structure.
The a-helices and b-sheets fold to form unique structures held together by bonds between amino acids that may be far apart in the actual polypeptide chain.
76
What is a quaternary protein structure?
Combined 3D structure of 2 or more polypeptide chains.
E.g. haemoglobin, consisting 2 alpha and 2 beta chains.
77
What are the 2 types of proteins (structural dependent)
Fibrous proteins, globular proteins
78
Describe structure of a fibrous protein.
Simple, elongated polypeptide chains arranged in parallel fashion along a single axis.
79
Describe structure of a globular protein.
Polypeptide chain folds up into a compact shape, like a ball with a rough surface.
80
Which of fibrous and globular proteins are water soluble/in-soluble?
Fibrous proteins are usu insoluble and stable; globular is usu water soluble
81
Describe differencesin the functions and nature between fibrous and globular proteins.
- Fibrous provide mechanical support and tensile strength and is more structural; globular is mobile and chemically active.
- Fibrous is less sensitive to changes in temperature, pH etc. Globular is more sensitive to changes in temp, pH.
82
Where are fibrous proteins found in our body?
Abundant outside the cell where they make up a lot of the matrix in between cells
83
Which of fibrous and globular proteins play crucial roles in nearly all biological processes and is more functional?
Globular proteins.
84
What is a proteome of a cell?
All the proteins that a cell makes
85
What does proteomics mean?
Study of the proteins in a cell.
86
What is a gene?
A segment of DNA, specifies the structure of a protein
87
What is a genetic code?
Specific arrangement of nucleotides in DNA and RNA that determine amino acid sequence of a specific protein.
88
What does gene expression mean?
Production of proteins from the information stored in DNA.
89
What does central dogma means?
A directional flow of info from DNA to RNA to protein.
90
What are the 2 steps in gene expression?
Transcription, translation.
91
Where do transcription and translation in protein synthesis occur?
Transcription: in nucleus;
Translation: in cytoplasm.
92
What happens during transcription?
Genetic info (a gene) is copied from the template strand of DNA to make a strand of ribonucleic acid (RNA), called mRNA (messenger RNA)
93
What happens in translation?
1. mRNA carries genetic info from nucleus to the ribosomes
2. sequence is "read" by translational machinery in the ribosome, in lots of three nucleotides (codon)
3. translation starts at the start codon (AUG) of each gene in the mRNA
4. Each codon codes for a specific amino acid
5. tRNA with a complimentary sequence (anticodon) binds to each triplet
6. tRNA also carries the amino acid specified by the codon
7. Amino acids joined together by peptide bonds, in the sequence specified by the mRNA, to make a peptide/protein.
94
What are the 2 strands of DNA?
Coding and template strands
95
Why is the coding strand important?
It contains the gene sequence.
96
What is the main function of the template strand of the DNA?
Making mRNA
97
How does transcription starts?
DNA unzip and uncoil. Then initiated by transcription factors that recruit RNA polymerase enzyme.
98
What region of the strand of DNA that RNA polymerase binds to?
Promoter region
99
________________ catalyses the formation of a mRNA chain following the rules of complimentary base pairing (A-U, C-G)
RNA polymerase
100
What indicate the gene to start and stops at transcription?
special sequences/signals in DNA
101
Where does transcription endson the coding sequence?
Terminator sequence
102
How does mRNA exits the nucleus?
Through nuclear pores into the cytoplasm.
103
Explain what is a polyribosome complex in the translation phase.
When multiple ribosomes read the same mRNA strand = multiple copies of proteins.
104
How many possible codons are there in mRNA?
64
105
What is the start codon?
AUG, aka methionine
106
What are the stop codons?
UAA, UAG, UGA
107
What is post-translational modification?
- Chemical modification of a protein following translation.
-amino acids may be cleaved off end of the protein or the polypeptide can be cut in half
- after translation, proteins can be modified by attaching other functional groups, which can change or extend its functions
- other modifications such as phosphorylation are a common way of controlling the behaviour of a protein, e.g. activating or inactivating an enzyme
108
What kind of cell undergoes mitosis?
Somatic cell
109
What kind of cell undergoes meiosis
Germ cell
110
What is germ cell and where are they located at?
It gives rise to gamete.
Located in the gonads (ovaries and testes)
111
What are gametes?
Cells that fuse during sexual reproduction. Sperm or egg (spermatocyte or oocyte)
112
How many chromosomes are in gamete?
23 chromosomes (haploid number)
113
Which phase do cells spend their majority (90%) of their life during a cell life cycle?
Interphase
114
What are the 3 phases of interphase?
G1 – normal metabolic activities
S – DNA replicates producing 2 identical copies of each
chromosome (new DNA is synthesised)
G2 – Cell prepares for division – organelles replicate
115
What does cytokinesis mean?
Division of cell organelles and cytoplasm. The final process of the cell division. Resulting in 2 identical daughter cells.
116
Describe mitosis in one sentence.
A series of events that leads to the production of two somatic cells by division of one mother cell into two daughter cells.
117
What is a locus in chromosomes?
The location of a gene on a chromosome.
118
Describe interphase in a cell life cycle.
DNA replication occurs, cell undergoes normal growth and normal metabolic processes and
prepares to divide.
119
Each chromosome consists of 2 _______________ (strands) connected by a ______________
Chromatids, centromere.
120
What are the 4 major types of cells in our body?
Somatic cell, germ cell, gamete, stem cell (stem cell is not a focus in HSF)
121
What is the major cell type that makes up most of the body of a multicellular organism (like humans)?
Somatic cell
122
What are some examples of somatic cell?
Neurons, muscle cells, epithelial cells
123
What is a zygote?
A diploid cell resulting from the fusion of two haploid gametes.
124
What stage comes first, interphase or mitosis?
Interphase
125
What is a sister chromatid?
Either of the two identical chromatids that are formed by replication of a chromosome during the S phase of the cell cycle, are joined by a centromere
126
What function does the action of chromatin wrapping around histone proteins have?
Protect the DNA so it doesn't get damaged during movement of cell division.
127
Which of X and Y chromosome is a lot smaller in size?
Y
128
In what phase of the cell life cycle does the DNA shows they are condensed into chromosomes, in a karyotype?
Metaphase
129
What are the initial stage of the cell and what occurs at interphase, where DNA replication occurs?
Initial stage: 2 individual chromosomes before replication, one homologous pair.
Interphase: each chromosome consists of 2 sister chromatids (strands) connected by a centromere.
130
Describe in what happens in prophase in mitosis?
Chromatin condenses into chromosomes; Each chromosome = two chromatids joined by a centromere.
The centrioles divide and move to each end of the cell.
Nuclear envelope disappears.
Microtubules form near the centrioles and project in different
directions, some project to equator of the cell.
131
Describe what happens in metaphase during mitosis?
Duplicated chromosomes (two chromatids) align along centre of the cell (equator).
Microtubules (spindle fibres) attach to centromere of each
chromosome (or to each sister chromatid).
132
Describe what happens in anaphase during mitosis?
The two chromatids of each chromosomes begin to separate.
The centromere that was holding the chromatids together divides.
The chromosomes assisted by the microtubules migrate towards the
centrioles.
Anaphase ends when the chromosomes reach the end of each cell.
Cytokinesis begins here.
133
Describe in what happens in telophase during mitosis?
The chromosomes unravel to become less obvious chromatin strands.
The nuclear envelop reforms and the microtubules disappear.
Cytokinesis continues.
134
At which phase does cytokinesis begins during a cell life cycle?
Almost the end of Anaphase
135
What is cytokinesis?
Cytoplasmic division
136
Describe meiosis in one short sentence.
Germ cells divide and produce gametes.
137
Two main divisions of meiosis, which of the first and second division dose the DNA replicates itself prior to it?
First phase
138
What are the 5 phases in the first meiotic division (meiosis 1)
1. Early prophase 1: Duplicated chromosomes become visible chromatids
2. Middle prophase 1: Homologous chromosomes line up next to each other, and cross over a bit of genetics = new gene combi, human variation
3. Metaphase 1: Homologous chromosomes align at center, random assortment of homologous chromosomes occur
4. Anaphase 1: Homologous chromosomes move apart to opposite of cell
5. Telophase 1: New nuclei form, and cell divides
139
At the end of meiosis 1, how many pairs of chromosome cells are there? Are the DNA replicated? Are they identical?
2 pairs of the 2 chromosome cells. Dna replicated and non-identical.
140
Why are DNA non identical at the end of meiosis 1?
There's DNA exchange between adjacent homologous chromatids in prophase 1 + random assortment of homologous chromosomes at metaphase 1 when they are align at the center of the cell.
141
How many cells are there at the beginning of meiosis 2? How many chromosomes are in each of them?
2, 23 chromosomes in each, DNA were replicated
142
What 4 phases do meiosis 2 go through?
1. Prophase 2: each chromosome consists of 2 chromatids
2. Metaphase 2: Chromosomes align along center of cell
3. Anaphase 2: chromatids separate and each now called a chromosome
4. Telophase 2: New nuclei form around chromosomes, then cell divides into 4 daughter cells with a haploid number of chromosomes
143
Where does meiosis happen?
In gonads
144
What does testes undergo to make gametes?
Meiosis
145
How many functional sperm cells per meiosis division?
4
146
How many functional oocyte cells per meiosis division?
1, the other 3 becomes polar bodies
147
What are examples of meiosis?
Spermatogenesis, oogenesis
148
When are all oocytes produced in human body?
At birth, oogenesis is not a life-long process.
149
Where does meiosis start on oocytes?
Prophase 1, when female hits puberty and this process occurs every month
150
What is the name of the process by which DNA is converted into mRNA and where does this event take place within the cell?
Transcription, which takes place in the cell’s nucleus.
151
What is the name of the process by which RNA is converted into protein and where does this event take place within the cell?
Translation, which takes place in the cytoplasm.
152
What happens to DNA before the cell can divide? Why is this so important?
It must replicate so that when cells divide, each new cell has the full amount of DNA
153
How and why does the cell package its DNA ready for division?
DNA condenses to form chromatin, which then winds up to form chromosomes.
Packaging the DNA in this way means it is protected during cell division and is easier to divide in half
154
What do the terms diploid and haploid mean? Give an example of a diploid cell and a haploid cell.
Diploid means a cell has the full amount of DNA e.g. all cells of the body except gametes. Haploid means a cell has half the amount of DNA e.g. gametes (sperm and egg)
155
Why do gametes only have a haploid amount of DNA?
Sperm and eggs only have half the amount of DNA (haploid) so that when a sperm fertilizes an egg the resulting embryo has the full correct amount of DNA (diploid).
156
What is a gene and what does it do?
A gene is a segment of DNA that codes for a particular protein
157
What is an allele?
A version of a gene.
You inherit one allele from each gamete (one from the oocyte and one from the spermatocyte) for every gene.
158
Make a list of the roles of proteins in the body, i.e. what do proteins do?
Enzymes, hormones, structural proteins e.g. collagen, receptors on the cell surface, transport e.g. cell membrane transport, transport of oxygen
159
What is the relationship of DNA to proteins?
DNA carries the code for the specific sequence of amino acids that form a particular protein.
160
Which of DNA and RNA molecules are shorter?
RNA
161
What are the main processes of protein synthesis involving DNA and RNA? (2 steps)
DNA code is transcribed into RNA code; then RNA is translated into amino acids, to form specific polypeptides and proteins.
162
Where is mRNA made? This is called transcription or translation?
In the nucleus, called transcription
163
How many nucleic acid bases code for one amino acid?
3, this group of 3 is called a CODON
164
What is the major role of mRNA?
takes the information from the genes (DNA) in the nucleus out to the ribosomes
165
What is the major role of transfer RNA (tRNA)?
Transfers amino acids from the cytoplasm to the ribosome and lines them up opposite their mRNA codon
166
What is the major role of ribosomal RNA (rRNA)?
Major structural component of the ribosome
167
Which amino acid has the same codon as the start codon? What does this tell you about all proteins?
Methionine has the same codon as the start codon.
All proteins originally start with this amino acid. However, short peptides are usually formed
by cutting up longer ones, so after processing, they don’t necessarily start with methionine
168
All cells, whether they line the stomach, lungs, or are found in the liver or brain; contain the same DNA, yet they all have very different structures and functions. How do you think this specialisation occurs?
Cells differ from other cells because they “turn on” different genes, and it is only genes that are turned on that are available for transcription and translation into proteins.
When a gene is “turned off” it means the cell will not make that particular protein.
Each time another gene is switched off, the cells functional abilities become more restricted, and the cell specialises (differentiates). This means the proteins made by, e.g., a muscle cell, are very different from those made by a liver cell, because they have very different functions.
169
What is the purpose of the first meiotic division?
Meiosis 1 separates homologous chromosomes, producing two haploid cells (23 chromosomes) which is half the amount of DNA in a “normal” cell. Thus, meiosis 1 is referred to as a reductional division
170
What do you think is the purpose of allowing some ‘swapping’ of bits of chromatid between members of homologous pairs during meiosis 1?
It increases genetic variation/variety in humans.
171
After the second meiotic division is completed, are the four haploid cells (i.e. cells with half the number of chromosomes) genetically identical?
Close – but no, the key is in the swapping or crossing over of chromatids.
172
How many alleles for a given gene does a gamete (sex cell) have?
One, because each gamete only has one copy of each chromosome, not two like a somatic (body) cell.
173
What is the difference between DNA replication vs transcription?
Replication = DNA replicating itself, making more DNAs
Transcription = DNA converting into mRNA
174
What does chromatid refers to?
It can be the more organized structured one side of the chromosome, or it can be the bundle of mess of strands of connected chromatins in the nucleus.
175
Can chromosome still be called chromosome if it has only one chromatid?
Yes
176
What's the relationship between centrosome vs centrioles?
A centriole is a barrel-shaped organelle which lives normally within the centrosome. 2 centrosomes, with 2 centrioles in each of them.
177
In which sub-phase during interphase does a cell replicate its centrosome?
G1 phase
178
In which phase during interphase does a cell replicate its DNA?
S phase (synthesize phase)
179
In which phase during interphase does all enzymes needed to aid cell division are produced in the cell?
G2 phase
180
Are germ cells diploid or haploid to start with?
Diploid, and meiosis turns them haploid in gametes, that are fused to form a diploid offspring
181
How many codons are there?
64
