Chapter #16 - Chromosomes, Genes and Proteins Flashcards
1
Q
Chromosomes
A
A length of DNA found in the nucleus. It contains genetic info in the form og different genes
2
Q
Under what circumstances can chromosomes be observed?
A
They can be seen with a regular light microscope only when cells are dividing
3
Q
What are chromososmes made of?
A
DNA in a double helix which is made up of genes
4
Q
How do chromososmes vary within your body?
(depending on what part of the body they are in)
A
Every cell in the body has all of it’s DNA. However, the cells are specialized to “read” only the parts that are rfelevent to that part of the body
5
Q
Draw a labled diagram of a chromosome
A
6
Q
DNA
A
A molecule that contains genetic info in the form of genes.
7
Q
What does DNA carry?
A
Each molecule of DNA carries a code whch the cell which proteins to make. So, each chromosome carries instructions for making diff proteins.
8
Q
Gene
A
A length of DNA molecule that coede for one protein.
9
Q
What do genes determine?
A
Many of our features such as:
* eye color
* hair color
* nose shape
* genetic diseases
10
Q
Alleles
A
Alternative forms of the same gene.
Moste genes come in more than one form.
11
Q
Homologous pair
A
A pair of chromosomes which are similar. In each pair, one is from the mother and the other from the father.
12
Q
Heterozygous
A
Having 2 different alleles of a particular gene (e.g. Gg).
13
Q
Homozygous
A
Having 2 identical alleles of a particular gene (e.g. GG or gg)
14
Q
How many chromosomes do humans have?
A
Humans have 46 chromosomes in each of our cells. (23 homologous chromosomes)
15
Q
Do all humans have the same types of alleles?
A
Humans have many genes in common but we differ in alleles. No 2 humans have the exact same combination of alleles (except for identical twins)
16
Q
The 46 chromosomes in a human body cell nucleus are difficult to distinguish when packed inside the nucleus. How are the similar pairs in the 46 chromosomes identified by scientists?
A
So, scientists seperate them and arrange them according to size and appearence.
17
Q
What chromosome pair does not match?
A
The sex chromosome. In males, the y chromosomes is smaller than the x chromosome.
18
Q
How are chromosomes organized and identified by scientists?
A
- Put into homologous pairs
- Order from largest to smallest
- They are numbered this way
19
Q
What are homologous pairs made up of?
A
One chromosome is inherited by the mother and the other from the father.
20
Q
Mitosis
A
The division of a cell nucleus resulting in 2 genetically identicle nuclei.
21
Q
When is mitosis used by animal or plant cells?
A
To repair or grow (also in aesexual reproduction)
22
Q
Replication
A
Before mitpsis begins, exact copies of all chromosomes are made.
23
Q
What steps occure during mitosis?
A
- Each chromosome spilts (after replication)
- 2 daughter cells that are genetically identicle yo eachother are produced
- They are also genetically identicle to parent cell
24
Q
Meiosis
A
The division of a diploid nucleus resulting in 4 genetically different haploid nuclei.
25
What else may meiosis be called?
Reduction division
26
Why is meiosis sometines called reduction division?
Because the number of chromososmes in the daughter cells is half that of in the parent cells.
27
Why is meiosis used?
To produce gametes (sex cells)
28
29
How many genes do humans have in their 46 chromosomes?
About 20000 human genes in our 46 chromosomes
30
What do chromosomes in a homologous pair have in common?
Each chromosome in a homologous pair contains genes for the same characteristics in the same position.
31
What does each gene contain?
Bases and therefore base pairs
32
What is the difference between a gene and an allele?
A gene specifies the trait, while the allele specifies which form of this trait the gene takes. (e.g. there could be a gene for eye color. The allele specifies that the eye color is brown.)
33
Genotype
The genetic makeup of an organism, including which alleles are used (e.g. bb or Bb or BB)
34
Phenotype
The observable features of an organism (e.g. brown eyes or blue eyes)
35
Dominant allele
An allele that is expressed if it is present (eg. G)
36
Recessive allele
an allele that is only expressed when there is no dominant allele present (eg. g)
37
Carriers
A recessive allele which is present but not expressed because of the precense of a dominant allele.
38
Codominance
alleles that are both present in the phenotype when they are both present.
39
What is an example of co-dominance?
40
What type of inheritance does the ABO blood group system demonstrate?
The ABO blood group system demonstrates codominance.
41
How is the gene for blood group represented, and how many alleles does it have?
The gene for blood group is represented with the capital letter I and has 3 alleles: I^A, I^B, I^O
.
42
What are the relationships between alleles for the blood group gene?
Both I^A and I^B are codominant and are both dominant to I^O
42
What is the blood group phenotype for the genotype I^A I^B
Blood group AB
42
What is the blood group phenotype for the genotype I^A I^O
Blood group O
42
What is the blood group phenotype for the genotype I^A I^A
Blood group A
43
What is the blood group phenotype for the genotype I^B I^B
Blood group B
44
What is the blood group phenotype for the genotype I^B I^O
Blood group B
45
What is the blood group phenotype for the genotype I^O I^O
Blood group O
46
Explain how the alleles for blood groups in humans demonstrate both dominace and codominance.
47
Inheritance
the transmission of genetic information from generation to generation
48
How can knowledge of genes and alleles help in inheritance?
Knowledge of genes and alleles can help make predictions about which characteristics will be passed on.
49
How is genetic information transferred?
Genetic informaton is transferred in gametes. Each gamete only has one of the homologous chromosome pair instead of 2 (23 chromosomes instead of 46).
Therefore there is only one of each pair of alleles.
50
What types of gametes would be produced by a male with genotype
𝐺𝑔?
Equal numbers of 𝐺 and 𝑔 sperm.
51
What type of gametes would be produced by a female with genotype 𝑔𝑔?
Eggs with only the 𝑔 allele.
52
What would happen if a 𝐺 sperm fertilizes a 𝑔 egg?
The resulting zygote would have the genotype 𝐺𝑔.
53
What would happen if a
𝑔 sperm fertilized a 𝑔 egg?
The resulting zygote would have the genotype 𝑔𝑔.
54
What determines the genotype of a zygote?
The genotype of the zygote is determined by the combination of alleles from the sperm and the egg during fertilization.
55
What are genetic diagrmas used for?
Used to show how to predict the probability of genotypes and phenotypes of the offspring of two parents.
56
Monohybrid cross
A diagram that a cross where we consider the inheritance of only one gene. (The one drawn on a table)
57
What is the monohybrid cross also referred as?
Punnet square diagram
58
Dictionary
The record of descent of an animal, showing it to be pure-bred.
59
Pedigree diagram
A chart used to show phenotypes (sometimes genotypes of family members in several generations.
60
In a pedigree diagram, how do you know what organisms are male or female?
| (when there is noe key)
61
In a pedigree diagram, how do you know what organisms are affected, or not, or something else (state what it is)?
62
What do the verticle lines in a pedigree diagrams represent?
They lead to offspring
63
What do horizontal lines represent in a pedigree diagram?
They show parents
64
What are the possible genotypes of an organism that expresses a dominant characteristic?
An organism that expresses a dominant characteristic could have two possible genotypes: homozygous dominant (e.g., 𝐴𝐴) or heterozygous (e.g., 𝐴𝑎).
65
How do we find out weather the genotype of an organism is dominant homozygous or heterozygous?
We could find out the genotype by crossing the individual with a homozygous recessive organism. If any of the offspring express the recessive gene, the organism was heterozygous.
66
What is the genetic makeup of pure-breeding organisms for a specific characteristic?
Pure-breeding organisms are always homozygous for the pure-breeding characteristic.
67
Sex chromosomes
Chromosomes that determine sex
68
X chromosome
The larger of the 2 sex xhromosomes in mammals
69
Y chromosome
The smaller of the two sex chromosomes
70
Each time someone has a child (regardless of how many children they have previously had) what is the chance of having a female or male?
50%
71
Do the X and Y chromosomes only determine sex?
No, the X and Y chromosomes don’t just determine sex; they also have other genes on them.
72
How do the X and Y chromosomes differ in size and number of genes?
The Y chromosome is tiny and contains only a few genes, while the X chromosome is larger and has many more gene
73
Why don’t people necessarily have two sets of genes on their sex chromosomes?
The Y chromosome is tiny and contains only a few genes, while the X chromosome has many more. Therefore, unlike other homologous pairs of chromosomes, sex chromosomes do not always carry two sets of genes
74
How do sex chromosomes differ from most homologous pairs of chromosomes? ( Show this in a diagram)
Most homologous pairs of chromosomes have identical sets of genes on both chromosomes. However, sex chromosomes (X and Y) differ:
* The X chromosome contains many genes, including sex-linked genes.
* The Y chromosome is smaller and contains genes that are not found on the X chromosome.
75
What are sex-linked genes, and what do they produce?
Genes that are only found on sex chromosomes are called sex-linked genes. They produce characteristics that are more common in one sex than the other.
76
What is an example of a sex-linked disease?
Red-green colour blindness
77
: What does a sex-linked gene control in the retina?
A sex-linked gene controls the production of the 3 different kinds of cone cells found in the retina.
78
What alleles makes someone red-green color-blind?
A sex linked gene controls the production of 3 diff. cone cells in the retina:
* A recessive allele of this gene = b = only 2 types of cone being made
* A dominant allele of this gene = B = all three are made.
79
What makes someone red-green color blind?
Someone who is homozygous recessive and has the allele bb.
80
How does red-green color-blidness affect males and females differently?
| (what is the percentage of females which have the disease compared to ma
This disorder affects about 8% of men and about 1% of women.
81
How does being red-green color-blind affect someone?
Sufferers are unable to tell the difference between red and green.
82
What is the role of nucleotide (base) sequences?
Sequences of nucleotides determine which amino acids are linked together to form a specific protein, and they also determine the protein's features, such as its shape.
83
How do sequences of nucleotides affect proteins?
Sequences of nucleotides determine which amino acids are linked together to form a specific protein, and they also determine the protein's features, such as its shape.
84
Where is DNA found?
In the nucleus
85
Where is mRNA created?
mRNA is created in the nucleus
86
What does mRNA do?
mRNA (messenger RNA) cerries information from DNA in the nucleus to ribosomes in the cytoplasm.
87
mRNA is **not** made in what shape?
In a double helix
88
What is a physical difference between DNA and RNA?
DNA is in a double helix while RNA is not. RNA is singke starnded.
89
How does mRNA work in steps?
1.
90
Why is it important that nucleotide sequences control the shapes of proteins?
So that functional enzymes are made with the right shapes to fit together (lock and key)
91
What is the 1st step of how proteins are made using mRNA?
* mRNA is created in the nucleus.
* It makes a copy of the sequence of bases in the DNA that make up a gene.
* The DNA stays in the nucleus.
92
What is the 2nd step of how proteins are made using mRNA?
mRNA moves out of the nucleus and into the cytoplasm
93
What is the 3rd step of how proteins are made using mRNA?
In a healthy person (eating a balanced diet) all the amino acids will be freely available in the cytoplasm.
The ribosome follows the code on the mRNA, and links together the necessary amino acids to form a chain (a protein.)
94
* mRNA is created in the nucleus.
* It makes a copy of the sequence of bases in the DNA that make up a gene.
* The DNA stays in the nucleus.
* mRNA moves out of the nucleus and into the cytoplasm
* In a healthy person (eating a balanced diet) all the amino acids will be freely available in the cytoplasm.
* The ribosome follows the code on the mRNA, and links together the necessary amino acids to form a chain (a protein.)
95
Stem cells
unspecialised cells that can divide by mitosis to form different types of specialized cells
96
Where can unspecialized cells be found?
* Newly formed embryos are made of stem cells
* Bone marrow => blood cells
* Brain cells => neurones
97
Bone marrow
Where stem cells are constantly dividing to form specialized cells for our blood such as red blood cells, platelets and lymphocytes.
98
Brain
Where stem cells divide to produce neurones
99
Are all the cells in your body genetically identical?
Yes, all the cells in your body are genetically identical and have a complete copy of your DNA, except for red blood cells and gametes.
100
Are all the cells in your body genetically identical, and do they use all the same genes?
Yes, all the cells in your body are genetically identical and have a complete copy of your DNA (except for red blood cells and gametes). However, they may only need to use some of the genes depending on their specific function.
101
What does it mean when a gene is expressed?
When the information from a gene is used to make a protein.
102
What is it called when the info. from a gene is used to make a protein?
We say the gene is expressed.
103
What does it mean when a gene is expressed, and how does this relate to specialized cells?
When the information from a gene is used to make a protein, the gene is said to be expressed. Each specialized cell only expresses the genes it needs to carry out its specific function.
104
How are newley formed embryo cells different from its cells in later stages?
Its cells have not yet developed and specialized, so they are stem cells.
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