Life Science Chapter 4

Front 1

What is the Cell Cycle?

Back 1

The cycle in which a cell grows and divides.

Front 2

What is interphase?

Back 2

A period of growth and development.

Front 3

What is mitosis?

Back 3

The process in which the nucleus of the cell divides to form two identical nuclei.

Front 4

What are all the phases in the cell cycle?

Back 4

Rapid growth (4hr), growth and DNA synthesis (10hr), growth and preparation for division (4hr), and mitosis (2hr).

Front 5

What happens in prophase?

Back 5

Chromosomes become visible, nucleolus and nuclear membrane disappear, centrioles move to opposite ends of the cell and spindle fibers begin to stretch across the cell.

Front 6

What happens in metaphase?

Back 6

The double-stranded chromosomes line up across the center of the cell and each centromere becomes attatched to a spindle fiber.

Front 7

What happens in anaphase?

Back 7

Each centromere divides and the two strands of each chromosome seperate. Strands then move toward opposite ends of the cell.

Front 8

What happens in telophase?

Back 8

Centrioles and spindle fibers disappear. Chromosomes stretch out and a nuclear membrane forms around each mass of chromosomes.

Front 9

What is a chromosome?

Back 9

Structures in the nucleus that contain DNA.

Front 10

What happens in plant cell mitosis?

Back 10

There are no centrioles, so a cell plate forms between the two nuclei and a cell wall forms on that cell plate.

Front 11

What is asexual reproduction?

Back 11

New organisms are produced from one parent.

Front 12

What is fission?

Back 12

The division of and organism into two equal parts.

Front 13

What is budding?

Back 13

A type of asexual reproduction in which a new organism grows from the body of the parent organiam.

Front 14

What is regeneration?

Back 14

An organism can repair damaged or lost body parts. A whole new organism may develop from just a piece of the organism.

Front 15

What is sexual reproduction?

Back 15

A new organism is produced when sex cells from two parents combine.

Front 16

What is a sperm?

Back 16

The sex cell from a male parent.

Front 17

What is and egg?

Back 17

The sex cell from a female parent.

Front 18

How many pairs of chromosomes are in a human body cell?

Back 18

23 pairs of 46 chromosomes.

Front 19

What is meiosis?

Back 19

The process of nuclear division that produces sex cells.

Front 20

What is diploid?

Back 20

When a cell has two of each chromosome it is said to be diploid.

Front 21

What is haploid?

Back 21

When a cell has one chromosome of each matched pair it is said to be haploid.

Front 22

What is fertilization?

Back 22

The joining of an egg and a sperm.

Front 23

What is a zygote?

Back 23

The cells that forms after fertilization.

Front 24

How is meiosis different from mitosis?

Back 24

In meiosis it happens twice, so it forms four cells and in anaphase 2 the centromere divides but not in anaphase 1.

Front 25

What is DNA?

Back 25

The chromosomes in the nucleus of a cell contain a code. This code is in the form of a chemical called deoxyribonucleicacid or DNA.

Front 26

Who is Scientist Rosalind Franklin?

Back 26

She discovered that the DNA molecule was a strand in a spiral form.

Front 27

Who are James Watson and Francis Crick?

Back 27

They made a DNA model.

Front 28

What are DNA molecules made out of?

Back 28

Two twisted strands of sugar phosphate strands, and nitrogen bases.

Front 29

What are the different kinds of nitrogen bases?

Back 29

Adenine, guanine, cytosine, and thymine.

Front 30

What do the different nitrogen bases match up with?

Back 30

Thymine matches up with adenine, guanine matches with cytosine.

Front 31

What are the steps in which DNA copies itself?

Back 31

1. An enzyme breaks the bonds between the nitrogen bases. The two strands of DNA separate. 2. The bases attach to each strand then pair up with new bases from the cytoplasm. The order of the base pairs in each new strand of DNA will match the original DNA. 3. Sugar and phosphate groups form the sides of each new DNA strand.

Front 32

What is a trait?

Back 32

A trait is are characteristics like what color your hair is and if you can digest milk or not.

Front 33

What is a gene?

Back 33

A gene is a section of DNA on a chromosome that directs the making of a specific protein. Genes control what traits you inherit.

Front 34

What is RNA?

Back 34

RNA is a type of nucleic acid.

Front 35

How is RNA different from DNA?

Back 35

RNA is single stranded, it has uracil in place of thymine, and there are two types of RNA. They are t-RNA and m-RNA.

Front 36

What is tRNA and what does it do?

Back 36

tRNA is short for transfer RNA and it picks up amino acids in the cytoplasm and brings them to the ribosomes. There, tRNA temporarily matches with mRNA and the amino acids become arranged according to the code carried by the mRNA.

Front 37

What is mRNA and what does it do?

Back 37

mRNA is short for messenger RNA and it moves out of the nucleus and attaches to the ribosomes. When the tRNA brings the amino acids to the ribosomes and get matched up, they bond together and a protein molecule begins to form.

Front 38

What is a mutation?

Back 38

Any permanent change in a gene or chromosome of a cell.

Front 39

How can mutations occur?

Back 39

Mutations can occur if an error is made when copying a gene. Outside factors such as X-Rays and chemicals have been known to change or break chromosomes.

Front 40

What happens if the mutation occurs in a sex cell?

Back 40

If a mutation occurs in a sex cell, all the cells that have formed from that sex cell will have the same mutation.

Front 41

Who cloned a sheep?

Back 41

Ian Wilmut, a Scottish scientist.

Front 42

What is a clone?

Back 42

A clone is an individual that is genetically identical to one of its parents.

Front 43

What are the steps for cloning?

Back 43

1. Scientists removed and egg from a sheep. Using a tiny needle, they took out the egg cell's nucleus. 2. Scientists remove a mammary gland cell from a female sheep. Placed cells together in a bath of chemicals. 3. Cells are fused by a jolt of electricity. 4. The fused cell, now complete with nucleus, begins dividing to form and embryo. 5. It is transferred to the uterus of a female sheep. The sheep that donated the mammary gland cell is the mother.

Front 44

Why aren't identical siblings clones?

Back 44

Because they received half the DNA from the father and half from the mother. A clone receives all its DNA from one parent.

Front 45

What is a differentiated cell?

Back 45

It is a cell that is specialized to perform a specific function in the body.

Front 46

Why was the birth of Dolly the sheep important?

Back 46

Because her growth was directed by the nucleus of a differentiated cell. Regular eggs have undifferentiated cells.

Front 47

when do the chromomes cross over in meiosis?

Back 47

prophase 1

Front 48

when do the centromeres split in meisosis?

Back 48

during anaphase 2