Bio Chap.4 Flashcards
What is the Cell Theory?
- All living things are composed of one or more cells.
- Cells are the smallest units of living organisms.
- New cells come only from pre-existing cells by cell division.
“Traits are passed on through _____ in the form of DNA”
genetic material
DNA stands for?
Deoxyribonucleic acid
What does the nucleus do in a cell?
The nucleus is the control centre of the cell and tells the cell what to do
What are chromosomes made up of?
Chromosomes are made up of DNA
What is inside the nucleus?
Inside the nucleus are some thread-like structures called Chromosomes.
What is DNA?
DNA is a chemical that contains the instructions that mean the cell can make a copy of itself.
What are sections of DNA called?
Genes
What are genes responsible for?
Genes are responsible for an organism’s features.
What are some examples of genes?
Ex; Eye colour, hair colour, skin colour, and height
What are the three functions of cell division in multicellular organisms?
Growth of the organism, repair of tissues and organs, and maintenance to replace dead cells
Somatic cell =?
Body cell (not including reproductive cells (gametes))
As one cell completes a cycle…
it becomes two cells
How long does the cell cycle last in most healthy, actively dividing animal cells?
12 to 24 hours
What are the 3 main stages in the cell cycle?
- Interphase: growth and intense cell activity
- Mitosis: The cell’s nucleus and genetic material divide
- Cytokinesis: division of the cell cytoplasm and creation of new cells.
Interphase is divided into what 3 phases?
Growth 1(G1), Synthesis (S), and Growth 2 (G2).
What is G1
G1 is the major period of growth.
What happens in the S phase?
S phase is when DNA (also called chromatin) is replicated.
What is G2?
G2 involves further growth and molecule synthesis.
What happens when DNA is replicated during Interphase?
The double helix unwinds and each strand of DNA serves as a template for a new strand. Each new double helix contains one original strand and one new strand.
What are the structures involved in Mitosis?
- Chromosomes
- Sister chromatid
- Centromere
- Spindle Fibre
- Centrosome
What is a chromosome?
A structure in the nucleus that contains DNA.
What is sister chromatid?
One of two genetically identical chromosomes and are held together at the centromere.
What is a centromere:
The region where two sister chromatids are held together in a chromosome.
What is spindle fibre?
A microtubule structure that facilitates the movement of chromosomes within a cell.
What is a centrosome?
A structure that helps to form the spindle fibres.
True or False: Is the process of cytokinesis different in different cell types?
True
How do animal cells divide during cytokinesis?
In animal cells, an indentation forms in the cell membrane along the cell’s equator. It deepens as the cytoplasm divides equally, and the cell pinches off into two cells.
How do plant cells divide during cytokinesis?
In plant cells, the rigid cell wall does not pinch inward. Instead, a new structure called a cell plate forms between the daughter nuclei. A cell wall forms on each side of the cell plate
What is DNA comprised of?
Nucleotides
What are Nucleotides made up of?
Sugar (deoxyribose), A phospahte group, and a base.
What are the 4 bases?
-Adenine (A)
-Guanine (G)
-Cytosine (C)
-Thymine (T)
Across the middle of the helix, what pair with what?
Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).
How is DNA shaped?
DNA is shaped like a long, spiralling double helix
How many chromosomes do humans have?
46
How many pairs of chromosomes do humans have?
23
1 of the 23 pairs of chromosomes are special, what are they?
Sex chromosomes
What are sex chromosomes?
An X or Y chromosome, which determines the genetic sex of an organism.
True or False: The two chromosomes, called X and Y are homologous.
False
XX = ?, XY = ?
Female, Male
What are the rest of the chromosomes called?
Autosomes
