Unit A 3.0 Flashcards
What does DNA stand for?
Deoxyribonucleic acid
What is DNA responsible for?
Variation
Is DNA inherited or herited?
Inherited
When was DNA first identified?
1869
Who discovered the structure of DNA?
Hint: 2 people
James Watson and Francis Crick
Who discovered the shape of DNA?
Hint: not a male 😏 ✊💜
Rosalind Franklin
What is the structure of DNA?
A double helix
What are the 4 kinds of nucleotides?
- Adenine
- Thymine
- Guanine
- Cytosine
What are the pairings of the nucleotides?
A-T
G-C
T/F: the arrangement of the nucleotides are like a blueprint of yourself.
True
The ____________ of these four chemicals create a language that cells can read
Arrangements
What are the nucleotides read in? (Ex. Singles, doubles, etc.)
Triples
What is the genetic code?
The arrangement of the genotypes made into a language the cells read.
T/F: The nucleotidal chemicals are the same for all species on Earth.
True
What are chromosomes?
They’re are packages within the cell which contain the DNA.
What are chromosomes found in? (Ex. Singles, pairs, etc.)
Pairs.
T/F: One chromosome contains all the instructions for making an organism.
False. Only some.
Where are chromosomes contained?
In the nucleus of the cell
T/F: All species have the same number of chromosomes.
False. It varies from species to species
Does the composition of the chromosomes vary from species to species?
Yes
How many individual chromosomal strands do humans have in each cell?
46 strands
How many chromosomal pairs do humans have in each cell?
23 pairs
If an animal has more than one nucleus in a cell, are the chromosomes spread out between them or are they just all in one?
All in one
Are genetics currently accepted in the scientific world?
Yes
What are genes responsible for?
Inheritance of an organism’s characteristic features.
What is a single gene?
An uninterrupted segment of DNA.
Where are genes located?
On the chromosomes.
T/F: Chromosomes have numerous gene locations
True.
What do genes come in? (Ex. Singles, pairs, etc.)
Pairs.
Does a pair of genes contain instructions for the same thing, or is each one different?
The same thing.
The same genes occupy ________ _________ on the chromosomes.
Matching locations.
Can the DNA code differ in each location?
Yes.
Are there different forms of genes coming from the parents?
Yes.
What are the different forms of genes called?
Alleles.
What is a codon?
A triplet of nucleotides (one word).
What is another word for nucleotides?
Nitrogenous bases.
What are the 2 things the wall of the DNA (not the rungs if the ladder, but the poles) is made of?
- Phosphates
2. Deoxyribose sugar
What holds the nucleotides together?
Hydrogen bonds.
What is the inside of the DNA?
The genetic code.
What is a karyotype?
The composition of the chromosomes and how many there are.
What do chromosomes contain?
The DNA.
How are the chromosomes organized?
By size.
Which are the letters for female?
XX.
Which are the letters for male?
XY.
What is an allele? (Written/Bb term)
One letter. B or b.
What is a gene? (Written/Bb term)
Both letters together. BB/Bb/bb.
NOT TO BE CONFUSED WITH GENOTYPE BASED ON THIS ANSWER.
Gene: ________.
Allele: ________.
Together
Apart
When together (now a gene), the alleles are _________.
Expressed.
What do alleles mean individually?
Nothing.
What does asexual reproduction produce?
Offspring genetically identical to the parent.
What does sexual reproduction produce?
Offspring genetically different to the parents.
Where does binary fission occur?
In unicellular organisms.
Give 2 examples of unicellular organisms.
Amoeba, paramecium.
How are the cell contents divided between the two new cells in any kind of cell division?
Equally.
What is the process that is essentially binary fission but it happens in multicellular organisms called?
Mitosis.
How does Mitosis work?
You start with one cell.
That cell then makes an exact copy of its DNA (2n [n = # of chromosomes]).
This cell now has twice its normal amount of DNA.
Binary fission occurs; the cell splits in 2.
Now, we have 2 identical daughter cells with the right amount of DNA.
1 —> 2
Where does mitosis happen?
On the body cells.
What is mitosis responsible for in multicellular organisms?
Growth and cellular repair.
What form of reproduction is mitosis?
Asexual.
T/F: Mitosis happens in every single organism in every single cell.
True.
How do body cells reproduce?
With mitosis.
Since mitosis occurs in body cells, what is it called?
Somatic.
List 2 factors of mitosis.
1 cell division, 2 identical offspring.
What does sexual reproduction require?
The fusion of two gametes (sperm cell, egg cell).
What would happen if each gamete had 23 pairs of chromosomes like the other cells?
The zygote would not survive if it had twice the amount of DNA it needed.
What happens when the gametes fuse?
A zygote is formed.
What comes after the zygote in the stages of reproduction?
An embryo.
What is meiosis?
NOT TO BE CONFUSED WITH MITOSIS!
A type of cell division that produces cells with only half the DNA of a normal cell.
What type of cell does meiosis create?
Gamete cells.
How many cell divisions does mitosis have?
1.
How many cell divisions does meiosis have?
2.
How many daughter cells does mitosis produce?
2.
How many daughter cells does meiosis produce?
4.
Identical daughter cells:
Asexual
Formation of sex cells:
Sexual
What is a diploid cell?
A cell that contains 2 copies of each chromosome (has twice its usual DNA).
How does meiosis work?
You start with one cell.
That cell then makes an exact copy of its DNA (2n [n = # of chromosomes]).
This cell now has twice its normal amount of DNA.
The exchange of DNA happens, where the chromosomes start to mix and join together.
Then the 1st binary fission/cell division happens, taking half of the DNA into each new cell. However, since the DNA mixed together, each chromosome now has a little bit of the other chromosome on it.
The second binary fission happens, and we now have 4 NON-identical cells.
These are gametes.
What type of cell are gametes?
Haploid cells; they have half the amount a normal cell does.
Each product of meiosis now has half the normal amount any other cell has, so it has __ singular strands. What will happen when it joins with the other gamete?
23
It will have 46 individual strands and 23 pairs, creating a zygote and having the proper amount to be a genetically normal person.
What does the process of meiosis ensure?
Variation.
Meiosis is the reason that…
We’re all different.
What form of reproduction is meiosis?
Sexual.
Are gametes involved in mitosis at all?
No.
What is selective/controlled breeding?
Breeding organisms with certain desired traits to get offspring with more desired traits.
What is a way to see which organisms to breed in selective breeding?
Patterns of inheritance.
What do genetics look at?
How heritable characteristics are passed on from one generation to the next.
Who did the work on genetics start with, and how did it start?
It started with Gregor Mendel, who traced patterns of inheritance through pea plants.
What is a purebred organism?
One who’s ancestors ALL had the same form of a trait.
What is a hybrid organism?
One who’s ancestors had different traits.
What is a dominant trait?
They’re those which are typically always expressed/observed if at least one is present.
What is a recessive trait?
They’re those which are only expressed/observed when two are present.
What does the dominant trait do to the recessive trait?
It masks it.
Define homozygous.
Purebred. Completely itself. BB, bb. Dominant or recessive shown, depending on whether it’s BB or bb.
Define heterozygous.
Hybrid. Different alleles. Bb. Dominant is always shown.
What is a genotype?
BB, Bb, bb. Those are all genotypes.
It’s the written code to show dominant and/or recessive traits.
What’s a phenotype?
Basically, the options. Not the combinations, but the possible outcomes.
Ex. Short, tall, brown, black, green, blue ,etc.
What trait is written as the uppercase letter?
Dominant.
What trait is written as the lowercase letter?
Recessive.
When are dominant traits expressed?
- When 2 dominant alleles are inherited
- When 1 dominant and 1 recessive allele are inherited
When are recessive traits expressed?
- When 2 recessive alleles are inherited
What is incomplete dominance?
A pattern of inheritance when the phenotype of the offspring matches neither of the parents, and are instead somewhere in between. Neither gene is truly recessive or truly dominant.
What can environmental factors cause?
Change in weight, height, skin colour, hair colour, etc.
If a baby gets deformed during pregnancy because of alcohol use by the parent, is that a genetic or environmental factor?
Environmental factor.
