[Part 2]- B12- reproduction 🧬 Flashcards
1
Q
What’s mitosis ?
A
- mitosis, is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA, produced by the parent cell during DNA replication
2
Q
RECAP: Describe the stages of the cell cycle [4]
Hint: growth of sub-cellular structures and…
A
- cell grows, and the number of sub-cellular structures [such as ribosomes and mitochondria] are increased.
- DNA then replicates to form two copies of each chromosomes
- In mitosis, one set of chromosomes is pulled to each end of the cell. The nucleus then divides
- the cytoplasm and cell membrane divides, to form two identical (daughter) cells
3
Q
What’s meiosis ?
A
- meiosis, is a type of cell division that gives rise to four reproductive cells [gametes], each with half the chromosome number of the parent cell.
4
Q
Where does meiosis take place ?
A
- meiosis only takes place in the reproductive organs.
- with humans this is the testes in males, and the ovaries in females
5
Q
What’s the process of meiosis ?
A
- firstly, all of the chromosomes are copied and the cell now divides into two.
- and these two cells, now divide one more time to form gametes
6
Q
What does meiosis do ?
A
- meiosis, halves the number of chromosomes.
- ; meiosis also produces four gametes from one original cell, that are all genetically different from each other
7
Q
- Fill in the gaps: each gamete has _________ alleles
A
- each gamete has different alleles
8
Q
What happens to gametes during fertilisation ?
A
- during fertilisation, gametes join together so the cell now has a normal number of chromosomes
- this means, fertilisation restores the full number of chromosomes
9
Q
What’s the difference between meiosis 🆚 mitosis ?
A
- meiosis, is a type of cell division that gives rise to four reproductive cells [gametes], each with half the chromosome number of the parent cell.
- ; mitosis, is the part of the cell cycle in which a eukaryotic cell divides to produce two daughter cells, each with the identical copies of DNA, produced by the parent cell during DNA replication
10
Q
What happens to a cell after fertilisation ?
A
- after fertilisation, the cell divides by mitosis to produce a clump of identical cells [known as an embryo]
11
Q
RECAP: What are the three functions of mitosis ?
A
- [mitosis is essential for] growth and development of multicellular organisms [e.g- plants and animals]
- mitosis takes place, when an organism repairs itself [e.g- when a broken bone heals]
- mitosis also happens during asexual reproduction
12
Q
Where is DNA found ?
A
- DNA is contained in structures known as chromosomes, which is then found in the nucleus of cells.
13
Q
What does DNA consist of ?
A
- DNA, consists of two strands and each strand is a polymer.
- this means, each strand is made by joining together lots of smaller molecules
14
Q
What is a double-helix ?
A
- a double-helix, is a term used to describe the physical structure of DNA, which involves two strands of nucleotides twisted around each other to form a shape [known as the double-helix]
15
Q
Define the term ‘gene’
A
- a gene, is a small section of DNA on a chromosome [that codes for a particular sequence of amino acids, to make a specific protein]
16
Q
Give an example, of how genes code a specific sequence of amino acids ?
A
- the blood type gene [chromosome number 9], codes sequence of amino aids for the protein that determines blood type.
- this is because, proteins are made by joining together amino acids
17
Q
How are chromosomes in pairs ?
A
- chromosomes are found in all body cells, except for gametes.
- these pair of chromosomes, are known as homologous pairs and have exactly the same genes, in the same location on the chromosome.
- this is because they’re inherited from each parent therefore, one member of each homologous pair will each come from the mother and the father
18
Q
What is the genome ?
A
- the genome, is the entire genetic material of an organism
- [the human genome, is the entire genetic material that makes a human]
19
Q
What’s the difference between a gene 🆚 a genome ?
A
- a gene, is a small section of DNA on a chromosome [that codes for a particular sequence of amino acids, to make a specific protein]
- ; the genome, is the entire genetic material of an organism
20
Q
Why is it important, that scientists have now studied the entire human genome ?
A
- understanding the human genome, helps us to search for genes that are linked to a disease [e.g- genes that increase the risk of developing a cancer, or alhezimers disease]
21
Q
What’s a second reason, why it’s important, to understand the entire human genome?
A
- understanding the human genome, helps us to understand and treat inherited disorders such as cystic fibrosis.
22
Q
What’s a third reason, why it’s important, to understand the entire human genome?
A
- the human genome, allows us to trace human migration patterns from the past- therefore, this can help people to discover their ancestry
23
Q
What are homologous pairs of chromosomes ?
A
- homologous pairs of chromosomes:
- carry the same genes in the same position, and are the same shape; they don’t necessarily carry the same alleles
[form] of each gene
24
Q
Why don’t homologous pairs of chromosomes, carry the same alleles ?
A
- the genes on these chromosomes may have been mutated as they passed down for generations, forming new alleles.
- these alleles typically perform the same function, such as determining eye color; they may have different outcomes due to the mutations they possess.
