lecture 6

Question 1

How do plants grow?

Answer 1

Plant cells start small they exchange materials with the environment and they grow through the interphase and start mitosis.

Question 2

How do plant cells divide into two?

Answer 2

Cell plate forms which is an accumulation of vesicles and divides the cell into two. This is for the plant cells.

Question 3

How does the sexual life cycle work?

Answer 3

In a human life cycle, zygote is a single cell which is a fertilized egg. We went from one cell to billions of cells today. Getting from zygot to billion of cells is a zygot. Each of us produce sperms and eggs which collectively are referred to as gametes. When the cells combine together the process of fertilization begins.

Question 4

What is haploid?

Answer 4

One complete set of genes. A haploid organism has one complete set of chromosomes. The number of chromosomes found in a haploid cell is different for each species. The number of chromosomes is designated by the letter n.

Question 5

What are diploid?

Answer 5

Having two complete set of genes or two complete sets of chromosomes. The number of chromosomes varies a lot and it is not related to the size of the organism.

Question 6

What type of organisms are diploid?

Answer 6

Humans are diploid organisms.

Question 7

What does being diploid mean?

Answer 7

Being diploid means we have homologous pairs. A diploid human cell has 23 homologous pairs.

Question 8

What does being haploid mean?

Answer 8

Haploid there is only 1 chromosomes from each homologous pair.

Question 9

What are examples of haploid organisms?

Answer 9

Gametes are always haploid. Human sperm has 23 chromosomes 1 from each homologous pair same for the egg.

Question 10

When are zygots diploid?

Answer 10

The zygot is diploid when it fuses the egg and the sperm. For each homologous pair one came from the egg and one from the sperm.

Question 11

What type of division do gametes use?

Answer 11

The gametes use a specialized cell division called meiosis. This only occurs in t he production of gametes.

Question 12

When does Meiosis start?

Answer 12

starts with they cell that started with the interphase.

Question 13

meiosis process

Answer 13

Meiosis has two cell divisions. Homologous pairs of chromosomes are together. Theres a pair of two chromosomes. There is a homologous pair. Crossing over when chromatids are physically crossing over in prophase 1 of meiosis. Chromosomes condense, spindle attach to the chromosomes at the centromere.

Question 14

Metaphase of meiosis I:

Answer 14

Homologous pairs of chromosomes lining up at the metaphase plate. The 4 chromosomes are still together. The spindles continue to pull and we get to anaphase.

Question 15

Anaphase I

Answer 15

Homologous pairs split, chromosomes are pulled to opposite ends. This is the transition from being diploid to being haploid. The cell elongates at this point. Only two chromosomes being sent to opposite sides of the cells. Some bits of DNA are being mixed between chromosomes in each homologous pair.

Question 16

Telophase I

Answer 16

New nucleus being formed in each end. The nuclear envelop assembles, the spindle breaks up, Each nuclei has two chromosomes one from each homologous pair. Cytokinesis begins. Each of the two cells is genetically unique.

Question 17

Cytokinesis I

Answer 17

There’s a cleavage furrow. The plasma membrane pinches cytoplasm in two. After this Meiosis I is complete. There is no interphase here. Just a brief pause and no growing happening here. Then Meiosis II starts here.

Question 18

What is meiosis II identical to?

Answer 18

Meiosis II is identical to mitosis.

Question 19

What happens during crossing over? and when does it happen?

Answer 19

When homologous chromosomes come together to form tetrads, the arms of the chromatids can swap at random, creating many more possibilities for genetic variation of the gametes.

Question 20

What do we start with and what is created during meiosis?

Answer 20

Start with 1 diploid cells Then we end up with 4 haploid cells. The haploid cells mature into gametes.
Matching pairs from mom and dad is a homologous pairs.

Question 21

Meiosis and sexual life cycles

Answer 21

It start with zygote, then cell cycle, then multicellular organism, few specialized cells that go through meiosis.
Meiosis produces haploid cells that then becomes gametes. The gametes meet other gametes and fuse together in fertilization and form a zygote. That is a typical animal cycle.

Question 22

Typical fungal life cycle

Answer 22

It starts with the zygote that goes right into meiosis. Goes from one diploid to 4 haploid. The haploid are not gamete, they are spores. If they land somewhere good they go through a cell cycle. The haploid cell goes through a cell cycle producing a multi cellular organism that is haploid. It continues through the cell cycle and produce gametes and can fuse together into fertilization to form a zygote.

Question 23

Typical plants and algae cycle

Answer 23

Start with the zygote. It goes into the plant life cycle. It becomes a diploid multicellular organism. Then it goes through meiosis and it produces spores not gametes. Those spores go through the cell cycle going through a cell cycle that are haploid. It can produce gametes. Those gametes go through fertilization and fuse together and form another zygote.

Question 24

Character or trait

Answer 24

A potentially variable quality or quantity in an organism.
Eg. flower colors, blood type, pea texture.

Question 25

True breeding variety

Answer 25

When an organism has new generation and always have the same traits in each generation.

Question 26

Hybrid

Answer 26

The offspring of two different varieties.

Question 27

Monohybrid cross

Answer 27

Studying the inheritance of a single character in a hybridization experiment.
P: parental generation: It is the starting point for the experiment.
F1: First Filial generation: The offspring of the P generation.
F2: Second filial generation: Offspring of the F1 generation

Question 28

explain the purple flower example

Answer 28

The parental generation was crossed (two true breeding variety)
F1 there were only purple flowers (one purple particle and one white particle)
F2 Then only one white and rest purple (the purple particles are dominant)

Question 29

Particles of inherintance

Answer 29

One particle makes the petals grow purple and one would be white. Each pea plant inherited two such particles. The dominant particle determines the color of the flower even when the other type of particle is there.

Question 30

Punnet square

Answer 30

The different combinations to be predicted in the next generation. For the second generation chance plays a bigger role in the genetic makeup of that generation.

Question 31

Gene

Answer 31

A sequence of genetic material (DNA).

Question 32

Locus

Answer 32

The place on a chromosome where a gene is located.

Question 33

Allele

Answer 33

One form of a gene found at a particular locus.

Question 34

Diploid

Answer 34

Having two alleles at each locus.

Question 35

Haploid

Answer 35

One allele at each locus.