3.2 - From one to many: the cell cycle

Question 1

What are autosomes?

Answer 1

all the chromosomes which aren’t sex chromosomes

Question 2

What is the locus?

Answer 2

position of a gene on a chromosome

Question 3

What are the 2 situations when are genes inherited independently?

Answer 3

1. if they are found on different chromosomes
2. if they are far apart on same chromosome

Question 4

What do we say when 2 genes have a locus on the same chromosome?

Answer 4

linkage

Question 5

what is likely to happen when 2 genes are linked?

Answer 5

they will be passed on as a pair of genes/inherited together into the same gamete

Question 6

What is autosomal linkage?

Answer 6

different genes with the same locus on the same autosome will tend to be passed on as a pair to the same gametes

Question 7

How does genetic variation occur through autosomal linkage?

Answer 7

independent assortment

Question 8

What are the 4 stages of mitosis?

Answer 8

1. prophase
2. metaphase
3. anaphase
4. telophase

Question 9

What happens in prophase?

Answer 9

• chromosomes condense & become visible as 2 strands
• centrioles move around nuclear envelope & position themselves at opposite sides of cell
• 2 poles of the spindle are formed & are involved in organisation of spindle fibres
• nuclear envelope is broken down

Question 10

What happens during metaphase?

Answer 10

• chromsomes’ centromeres attach to spindle fibres at equator

Question 11

What happens during anaphase?

Answer 11

• centromeres split
• spindle fibres shorten, pulling 2 halves of each centromere in opposite directions
• one chromatid of each chromosome to each of the poles
• spindle breaks down

Question 12

What happens in telophase?

Answer 12

• chromosomes unravel & nuclear envelope reforms, so 2 sets of genetic information become enclosed in separate nuclei

Question 13

What is widest part of the spindle called?

Answer 13

equator

Question 14

What is the more unofficial stage of mitosis?

Answer 14

cytoplasmic division

Question 15

What happens during cytoplasmic division?

Answer 15

• the whole cell divids and one nucleus moves into each cell to create two genetically identical daughter cells
  (in animal cells) - involves constriction of cytoplasm & (in plant cells) - a new cell wall is formed

Question 16

What are the sex chromosomes for females? And for males?

Answer 16

XX - females
XY - males

Question 17

What is sex linkage?

Answer 17

when genes on the sex chromosomes are found at the same locus and passed on with those that determine sex